Considering the solution of mole fraction, molality and molarity, you obtain that:
(a) the mole fraction of thiophene in the solution is 0.039.
(b) the molality of thiophene in the solution 0.4429 [tex]\frac{moles}{kg}[/tex].
(c) the molarity of thiophene in the solution is 0.373[tex]\frac{moles}{L}[/tex].
You know that:
Density toluene (C₇H₈)= 0.867 [tex]\frac{g}{mL}[/tex]Density thiophene (C₄H₄S)= 1.065 [tex]\frac{g}{mL}[/tex] Volume of toluene (C₇H₈)= 250 mL= 0.250 L (being 1000 mL= 1 L)Mass of thiophene (C₄H₄S)= 8.10 grams(a) Mole fractionThe molar fraction is a way of measuring the concentration that expresses the proportion in which a substance is found with respect to the total moles of the solution.
Being the molar mass of each compound equals to:
Toluene (C₇H₈)= 92 [tex]\frac{g}{mol}[/tex]Thiophene (C₄H₄S)= 84 [tex]\frac{g}{mol}[/tex]the number of moles of each compound can be calculated as:
Toluene (C₇H₈)= [tex]250 mLx\frac{0.867 grams}{1 mL} x \frac{1 mole}{92 grams}[/tex]= 2.35 molesThiophene (C₄H₄S)= [tex]8.10 gramsx\frac{1 mole}{84 grams}[/tex]= 0.096 molesThe total moles is obtained from the addition of the moles of the solute (C₄H₄S) and the solvent (C₇H₈):
total moles = moles C₄H₄S + moles C₇H₈ = 0.096 moles + 2.35 moles = 2.45 moles
Then, the mole fraction of thiophene in the solution can be calculated as:
[tex]mole fraction of thiophene=\frac{0.096 moles}{2.45 moles}[/tex]
Solving:
mole fraction of thiophene= 0.039
Finally, the mole fraction of thiophene in the solution is 0.039.
(b) MolalityMolality is the ratio of the number of moles of any dissolved solute to kilograms of solvent.
The Molality of a solution is determined by the expression:
[tex]Molality=\frac{number of moles of solute}{kilograms of solvent}[/tex]
In this case, you know:
number of moles of solute (C₄H₄S)= 0.096 moles Mass of solvent = [tex]250 mLx\frac{0.867 grams}{1 mL}[/tex] = 216.75 g = 0.21675 kg (being 1000 g=1 kg)Replacing:
[tex]Molality C_{4} H_{4}S =\frac{0.096 moles}{0.21675 kg}[/tex]
molality C₄H₄S= 0.4429 [tex]\frac{moles}{kg}[/tex]
Finally, the molality of thiophene in the solution 0.4429 [tex]\frac{moles}{kg}[/tex].
(c) MolarityMolarity is the number of moles of solute that are dissolved in a certain volume and is determined by the following expression:
[tex]Molarity=\frac{number of moles of solute}{volume}[/tex]
Assuming that the volumes of solute and solvent are additive, you can add the volume of C₄H₄S and C₇H₈.
But first, you need yo know the volume of C₄H₄S, which can be calculated from the mass and density:
[tex]Volume C_{4} H_{4}S =8.10 grams\frac{1 mL}{1.065 grams}[/tex]= 7.606 mL= 0.007606 L
Then, the total volume of the solution is calculated as:
total volume of the solution= volume C₇H₈ + volume C₄H₄S
total volume of the solution= 0.250 L + 0.007606 L = 0.257606 L
So, the molarity of thiophene in the solution can be calculated as:
[tex]Molarity C_{4} H_{4} S=\frac{number of moles of C_{4} H_{4} S}{totalvolumeof the solution}[/tex]
Replacing:
[tex]Molarity C_{4} H_{4} S=\frac{0.096 moles}{0.257606 L}[/tex]
Solving:
Molarity C₄H₄S= 0.373 [tex]\frac{moles}{L}[/tex]
Finally, the molarity of thiophene in the solution is 0.373[tex]\frac{moles}{L}[/tex].
In summary, you get:
(a) the mole fraction of thiophene in the solution is 0.039.
(b) the molality of thiophene in the solution 0.4429 [tex]\frac{moles}{kg}[/tex].
(c) the molarity of thiophene in the solution is 0.373[tex]\frac{moles}{L}[/tex].
Learn more about
density: brainly.com/question/952755?referrer=searchResults brainly.com/question/1462554?referrer=searchResults mole fraction: brainly.com/question/14434096?referrer=searchResults brainly.com/question/10095502?referrer=searchResults molality brainly.com/question/20366625?referrer=searchResults brainly.com/question/4580605?referrer=searchResults molarity with this example: brainly.com/question/15406534?referrer=searchResultsplease help me please help me
How can your knowledge of acids and bases
help you approach this problem to keep your soil
viable?
HELP NOW
Answer:
How can we make use of acids or bases to remove heavy metals from soils? We can remove heavy metals from soil by adding acid and catching the solution that drains through. Acids can react with metals turning metalic compounds which can be dissolved by water and washed away. Improve crop yields?
Explanation:
Pressure is often defined as
Answer:
Pressure is often defined as a measure of force applied on an area, or over a unit area.
Explanation:
Compound is a dull white smooth solid which does not conduct electricity.
a. True
b. False
Answer:
a. True.
Explanation:
Hello!
In this case, since dullness and smoothness are characteristic of materials that are not able to conduct the electricity, as they do not provide an appropriate pathway for the electrons to move around because of their amorphous structure, we realize the answer is a. True.
On the contrary, a lustrous and robust solid, is actually able to conduct electricity because it provides the pathway for the electron movements and therefore to conduct electricity.
Best regards!
Thermal energy is the energy an object has due to the _____ of the particles
Answer: Vibråtory movement.
Explanation: when particles bounce against each other the friction creates thermal energy. Think about what happens when you rub your hands together and they get warmer, that the friction between your hands making thermal energy.
What is the coefficient, subscript for V, and subscript for O in V2O5
Answer: Coefficient 0
subscript for V 2
subscript for O 5
Explanation: yes
There is no coefficient in V₂O₅ and the subscript of vanadium V is 2 and the subscript of oxygen is 5.
What is vanadium pentoxide ?Vanadium pentoxide is an ionic compound formed by donating electrons from the vanadium metal to oxygen. The chemical formula of vanadium pentoxide is V₂O₅.
The chemical formula of a compound is written in terms of the chemical symbol of each constituent elements and the number of their atoms. The number of atoms is written as subscript for the chemical symbols.
In V₂O₅, there are are 2 vanadium atoms and 5 oxygen atoms. Coefficients are numbers prior to the formula in reaction. Here there is no coefficient and the subscript for V is 2 and that of O is 5.
Find more on chemical formula:
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When performing a multiplication or division calculation, significant figures in the calculated result are dictated by the _____ of the measured numbers.
The calculated result should have ______ the measured number in the calculation with the fewest _______.
Answer:
fewest; the same significant figures with; measured numbers.
Explanation:
Without mincing words let us dive straight into the solution to the above question. In order to be able to use the significant figures properly one must know the rules attached to it uses. This is so, because they contributes to the precision of measurements.
When performing multiplication or division calculation, the number of significant figures in the answer[result] will be determined by the one with the smallest number of significant figure in the problem. Therefore, if we have 6.56 which is three[3] significant figures and 1.2 which is two[2] significant figures, then the number of significant figures will be two[2].
6.56 × 1.2= 7.872 = 7.9[ to 2 significant figures].
PLEASE HELP PLEASE LLEASE HELP, WILL MARK BRAINLIEST!!!
Which of the following elements will NOT reach an octet when in a bond?
Answer:
Hydrogen
Explanation:
the gravitational force between two objects depends on the distance between the objects and each object?
Answer:
Gravitational force between two objects depends on: a. The weight of the objects c. The mass of each object b. The distance between the objects d. Both b and c Please select the best answer from the choices provided A B C D
✓d
Which of the statements about liquids and gases are true?
Both liquids and gases have a definite volume.
O The particles in liquids and gases can move past one another
freely
Both liquids and gases have a definite shape.
Neither liquids nor gases have a definite shape.
Which of the statements about liquids and gases are true?
Answer:The particles in liquids and gases can move past one another freely.
#CARRYONLEARNING #STUDYWELLWhich of the statements about liquids and gases are true?
Choosing:Both liquids and gases have a definite volume.
The particles in liquids and gases can move past one another freely
Both liquids and gases have a definite shape.
Neither liquids nor gases have a definite shape.
Answer:The particles in liquids and gases can move past one another freely.
#READINGHELPSWITHLEARNING #CARRYONLEARNING #STUDYWELLMy question my question
H2O as an oxidant only
Further explanationGiven
Reaction
2 Na + 2 H2O → 2 NaOH + H2
Required
The function of water in the equation
Solution
Water : oxidizing agent
Na : reducing agent
Na⁰ → Na⁺ (oxidation)
H⁺- → H⁰ (reduction)
Acids and bases according to Bronsted-Lowry
Acid = donor (donor) proton (H⁺ ion)
Base = proton (receiver) acceptor (H⁺ ion)
If water is acting as an acid it should only give 1 H +, so that becomes:
H₂O (l) ⇔ OH⁻ (aq) not H₂
which mineral is composed of calcium and fluorine?
Answer:
Fluorite
What is Fluorite? Fluorite is an important industrial mineral composed of calcium and fluorine (CaF2). It is used in a wide variety of chemical, metallurgical, and ceramic processes
A mixture is made by combining 1.29 lb of salt and 5.35 lb of water.
What is the percentage of salt (by mass) in this mixture?
Answer:
19.47%
Explanation:
[tex]\frac{1.29}{1.29+5.35}[/tex]
Please recheck, for this answer may not be correct
How many electrons does a single hydrogen gain or lose in the following reaction?
H2 + O2 - H20
Answer:
One electron per single hydrogen atom.
Explanation:
Hello!
In this case, given the reaction:
[tex]H_2+O_2\rightarrow H_2O[/tex]
Whereas we can identify the following half-reaction for hydrogen:
[tex]H_2^0\rightarrow H_2^+[/tex]
Whereas we see that each single hydrogen atom gains one electron in order to go from 0 to +1, which is also related to an oxidation half-reaction.
Best regards!
a sample of solid is decomposed and found to contain 6.52g of potassium, 4.34 g of chromium and 5.34 of oxygen, what is the empirical formula of the compound? help asap
Answer:
K₂CrO₅
Explanation:
The empirical formula is the simplest formula of a compound. To find the empirical formula, we follow the procedure below:
Elements Potassium Chromium Oxygen
Mass 6.52 4.34 5.34
Molar mass 39 60 16
Number of moles 6.52/39 4.34/60 5.34/16
0.167 0.072 0.333
Divide through by
the smallest 0.167/0.072 0.072/0.072 0.333/0.072
2.3 1 4.6
2 1 5
Empirical formula K₂CrO₅
Select the correct number of valence electrons, in order, for groups 13-18.
13, 14, 15, 16, 17, 18
5, 6, 4, 3, 8,7
3,4,5,6,7,8
18, 13, 15, 16, 17, 14
Answer:
3,4,5,6,7,8
Explanation:
Groups 13 - 18 are the main group on the periodic table
The group number corresponds the number of valence electrons they contains.
Valence electrons are the number of electrons in the outermost shell of an atom.
So group 13 - 18 corresponds to a valency of 3,4,5,6,7,8.
Groups with a valency of 8 are the noble gases.
Questlon 23 of 30
What is the term for a large group of people with similar characteristics such
as educational background and income level?
A. An interest group
B. A social class
C. A social culture
O D. A political party
SUBMIT
How many electrons must nitrogen gain to become like it’s closest noble gas, Neon?
Answer:
3
Explanation:
Compound A reacts with Compound B to form only one product, Compound C, and it's known the usual percent yield of C in this reaction is 72.%. Suppose 3.5g of A are reacted with excess Compound B, and 6.5g of Compound C are successfully isolated at the end of the reaction.
A. What was the theoretical vield of C?
B. How much B was consumed by the reaction?
Answer:
A. Theoretical yield of C is 9.03 g
B. Mass of B consumed is 5.53 g
Explanation:
A. Determination of the theoretical yield of C.
Actual yield of C = 6.5 g
Percentage yield of C = 72.%
Theoretical yield of C =?
Percentage yield = Actual yield /Theoretical yield × 100
72% = 6.5 / Theoretical yield
72 / 100 = 6.5 / Theoretical yield
Cross multiply
72 × Theoretical yield = 100 × 6.5
72 × Theoretical yield = 650
Divide both side by 72
Theoretical yield = 650 / 72
Theoretical yield = 9.03 g
Therefore, the theoretical yield of C is 9.03 g
B. Determination of the mass of B consumed.
We'll begin by writing the balanced equation for the reaction. This is illustrated below:
A + B —> C
Mass of A = 3.5 g
Mass of C = 9.03 g
Mass of B =?
A + B = C
3.5 + B = 9.03
Collect like terms
B = 9.03 – 3.5
B = 5.53 g
Thus, the mass of B consumed in the reaction is 5.53 g
. Predict the possible products for the following reaction and include
molecular, complete ionic, and net ionic equations.
NA2SO4 (aq) +γ (BrO3)2 (aq) --->
Answer:
Introduction
As a diligent student of chemistry, you will likely encounter tons of reactions that occur in aqueous solution (perhaps you are already drowning in them!). When ions are involved in a reaction, the equation for the reaction can be written with various levels of detail. Depending on which part of the reaction you are interested in, you might write a molecular, complete ionic, or net ionic equation.
Definitions of molecular, complete ionic, and net ionic equations
A molecular equation is sometimes simply called a balanced equation. In a molecular equation, any ionic compounds or acids are represented as neutral compounds using their chemical formulas. The state of each substance is indicated in parentheses after the formula. [Huh?]
Let's consider the reaction that occurs between \text{AgNO}_3AgNO
3
start text, A, g, N, O, end text, start subscript, 3, end subscript and \text{NaCl}NaClstart text, N, a, C, l, end text. When aqueous solutions of \text{AgNO}_3AgNO
3
start text, A, g, N, O, end text, start subscript, 3, end subscript and \text{NaCl}NaClstart text, N, a, C, l, end text are mixed, solid \text{AgCl}AgClstart text, A, g, C, l, end text and aqueous \text{NaNO}_3NaNO
3
start text, N, a, N, O, end text, start subscript, 3, end subscript are formed. Using this information, we can write a balanced molecular equation for the reaction:
\text{AgNO}_3(aq) + \text{NaCl}(aq) \rightarrow \text{AgCl}(s) + \text{NaNO}_3(aq)AgNO
3
(aq)+NaCl(aq)→AgCl(s)+NaNO
3
(aq)start text, A, g, N, O, end text, start subscript, 3, end subscript, left parenthesis, a, q, right parenthesis, plus, start text, N, a, C, l, end text, left parenthesis, a, q, right parenthesis, right arrow, start text, A, g, C, l, end text, left parenthesis, s, right parenthesis, plus, start text, N, a, N, O, end text, start subscript, 3, end subscript, left parenthesis, a, q, right parenthesis
[What kind of reaction is this?]
If we could zoom in on the contents of the reaction beaker, though, we wouldn't find actual molecules of \text{AgNO}_3AgNO
3
start text, A, g, N, O, end text, start subscript, 3, end subscript, \text{NaCl}NaClstart text, N, a, C, l, end text, or \text{NaNO}_3NaNO
3
start text, N, a, N, O, end text, start subscript, 3, end subscript. Since \text{AgNO}_3AgNO
3
start text, A, g, N, O, end text, start subscript, 3, end subscript, \text{NaCl}NaClstart text, N, a, C, l, end text, and \text{NaNO}_3NaNO
3
start text, N, a, N, O, end text, start subscript, 3, end subscript are soluble ionic compounds, they dissociate into their constituent ions in water. For example, \text{NaCl}NaClstart text, N, a, C, l, end text dissociates into one ion of \text{Na}^+Na
+
start text, N, a, end text, start superscript, plus, end superscript for every ion of \text{Cl}^-Cl
−
start text, C, l, end text, start superscript, minus, end superscript; these ions are stabilized by ion-dipole interactions with the surrounding water molecules. [I don't get it!]
Image of crystalline sodium chloride next to image of chloride and sodium ions dissociated in water. Each chloride ion is interacting with multiple water molecules through the positive dipole of the water, and each sodium ion is interacting with water molecules through the negative dipole of the water.
Image of crystalline sodium chloride next to image of chloride and sodium ions dissociated in water. Each chloride ion is interacting with multiple water molecules through the positive dipole of the water, and each sodium ion is interacting with water molecules through the negative dipole of the water.
Sodium chloride dissociates into sodium and chloride ions in water, and these ions become solvated by the highly polar water molecules. Image credit: "Salts: Figure 1" by OpenStax Anatomy and Physiology, CC-BY-NC-SA 4.0.
From the molecular formula, we can rewrite the soluble ionic compounds as dissociated ions to get the complete ionic equation:
\text{Ag}^+(aq) + \blueD{{\text{NO}_3}^-(aq)} + \maroonD{\text{Na}^+(aq)} + \text{Cl}^-(aq) \rightarrow \text{AgCl}(s) + \maroonD{\text{Na}^+(aq)} + \blueD{{\text{NO}_3}^- (aq)}Ag
+
(aq)+NO
3
−
(aq)+Na
+
(aq)+Cl
−
(aq)→AgCl(s)+Na
+
(aq)+NO
3
−
−
(aq)
+
Na
+
(aq)
+Cl
−
(aq)→AgCl(s)+
Na
+
(aq)
+
NO
3
−
(aq)
All the iron in a 2.000 g tablet was dissolved in an acidic solution and converted to Fe2+. This was then titrated with KMnO4. The titration required 27.50 cm3 of 0.100 mol dm-3 KMnO4. Calculate the total mass of iron in the tablet and its percentage by mass.
Answer:
0.768g of Fe are in the tablet = 38.4% by mass of Fe in the tablet
Explanation:
The balanced redox equation of Fe²⁺ with KMnO₄ in acidic medium is:
5Fe²⁺ + MnO₄⁻ + 8H⁺ → 5Fe³⁺ + Mn²⁺ + 4H₂O
Where 5 moles of Fe²⁺ react per mole of KMnO₄
The moles required of KMnO₄ are:
27.50cm³ * (1dm³ / 1000cm³) = 0.0275dm³ * (0.100mol / dm³) = 0.00275mol KMnO₄
Moles of Fe²⁺ are:
0.00275mol KMnO₄ * (5 moles Fe²⁺ / 1mol KMnO₄) = 0.01375moles of Fe²⁺
In grams (Molar mass Fe: 55.845g/mol):
0.01375moles of Fe²⁺ * (55.845g/mol) =
0.768g of Fe are in the tabletAnd percentage is:
0.768g Fe / 2.000g * 100 =
38.4% by mass of Fe in the tabletThe data below shows the change in concentration of dinitrogen pentoxide over time, at 330 K, according to the following process.
2N2O5(g) = 4NO2(g) + O2
[N2O5] Time (s)
0.100 0.00
0.066 200.00
0.044 400.00
a) Find the rate of disappearance of N2O5 from t=0 s to t=200s
b) Find the rate of appearance of NO2 from t=0 s to t =200s
Answer: a) [tex]1.7\times 10^{-4}[/tex]
b) [tex]3.4\times 10^{-4}[/tex]
Explanation:
The reaction is :
[tex]2N_2O_5(g)\rightarrow 4NO_2(g)+O_2(g)[/tex]
Rate = Rate of disappearance of [tex]N_2O_5[/tex] = Rate of appearance of [tex]NO_2[/tex]
Rate = [tex]-\frac{d[N_2O_5]}{2dt}[/tex] = [tex]\frac{d[NO_2]}{4dt}[/tex]
Rate of disappearance of [tex]N_2O_5[/tex] = [tex]\frac{\text {change in concentration}}{time}[/tex] = [tex]\frac{0.100-0.066}{200-0}=1.7\times 10^{-4}[/tex]
a) Rate of disappearance of [tex]N_2O_5[/tex] = [tex]-\frac{d[N_2O_5]}{2dt}[/tex]
Rate of appearance of [tex]NO_2[/tex] = [tex]\frac{d[NO_2]}{4dt}[/tex]
b) Rate of appearance of [tex]NO_2[/tex] = [tex]\frac{d[NO_2]}{dt}=2\times 1.7\times 10^{-4}}=3.4\times 10^{-4}[/tex]
A) Find the rate of disappearance of [tex]N_2O_5[/tex] from t = 0 s to t = 200s
[tex]Rate = \frac{1}{2}(\frac{-\delta N_2O_5}{\delta t})\\\\Rate = -\frac{1}{2}(\frac{0.066 - 0.100}{200 - 0})\\\\Rate = 8.5*10^{-5}[/tex]
B) Find the rate of appearance of [tex]NO_2[/tex] from t = 0 s to t = 200s
According to rate law,
[tex]\frac{1}{2}(\frac{-\delta N_2O_5}{\delta t}) = \frac{1}{4}(\frac{\delta NO_2}{\delta t})\\\\8.5*10^{-5} = \frac{1}{4}(\frac{\delta NO_2}{\delta t})\\\\\frac{\delta NO_2}{\delta t} = 4 * 8.5*10^{-5}\\\\Rate = 3.4*10^{-4}[/tex]
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9. What metric unit would be most
appropriate to use when measuring
the length of a paperclip?
a. Millimeter
b. Decimeter
c. Meter
d. Kilometer
Answer: a. Millimeter
Explanation:
A paperclip is a small device or instrument that can be used to hold the papers or stack of papers together. The length of the paperclip can be measured using millimeter. It is equal to the thousands of meters. The millimeter is a dimension which is used to measure the very small length objects which have visible scale distances and length.
Decimeter can be used to measure the length of the object smaller than paperclips. Meter and kilometers are used for objects and distances larger than paperclip.
Classify each of the observed changes according to whether or not they are likely to represent evidence that a chemical reaction is occurring when performing an experiment.
May be evidence of a chemical reaction Not evidence of a chemical reaction
a solution color becoming less intense
due to dilution
bubbles (sas formation) changes in color
precipitation
explosion or fire
Answer Bank
a solid liquifying change in temperature solution colors mixing
Answer:
a solution color becoming less intense due to dilution- is not an evidence of a chemical reaction
bubbles (gas formation) - evidence of a chemical reaction
explosion or fire - evidence of a chemical reaction
changes in color- evidence of a chemical reaction
precipitation- evidence of a chemical reaction
changes in temperature - evidence of a chemical reaction
a solid liquifying - is not an evidence of a chemical reaction
solution colors mixing - is not an evidence of a chemical reaction
Explanation:
A chemical change is not easily reversible and yields new substances. It is often accompanied by a loss or gain of heat.
In the answer section, i have shown some evidences that lead us to conclude that a chemical reaction has taken place. The occurrence of a chemical change often goes with the formation of new substances as earlier stated and any of these signs may accompany the process.
For instance, when a metal is dropped in dilute acid solution, bubble of hydrogen gas indicates that a chemical reaction has taken place.
Which of the below elements are part of a group? Feel free to use the periodic table.
A. H, He, O, C
B. Be, Mg, Ca, Sr
C. Li, Be, C, O
D. H, Li, Na, Mg
Answer:
B. Be, Mg, Ca, Sr
Explanation:
Be, Mg, Ca, Sr are parts of the alkaline Earth metal family/group. So they are the second most reactive elements following behind alkali metals. Furthermore, Be, Mg, Ca, Sr all have 2 valence electrons that lose them to form cations. They have low melting points, low boiling points, can conduct electricity, have high malleability and ductility.
Hope it helped!
which toxic gas is released in incomplete combustion?
Answer:
Incomplete combustion produces carbon monoxide (CO), a toxic gas.
Explanation:
Combustion is the rapid chemical reaction of oxygen in the air or direct oxygen, which is defined as oxidizer, with the different elements that make up the fuel (mainly carbon (C) and hydrogen (H)). These chemical reactions release energy producing local increases in temperature, which causes a flow of heat to the outside.
In other words, on the one hand you have the fuel, which is the substance that oxidizes and that you can find in a solid, liquid or gaseous state and which is made up mostly of carbon and hydrogen.
The oxidizer, for its part, is the substance that oxidizes the fuel, and it is generally the oxygen found in the air.
Certain amounts of oxidizer and fuel must come into contact for combustion to occur.
Incomplete combustion occurs when part of the fuel does not fully react. Incomplete combustion produces carbon monoxide (CO), a toxic gas.
How many moles are in the following:
7.36 x 1024 of free Oxygen atoms
Answer: 12.2 moles
Explanation:
7.36x10^24/6.02214076x10^23 = 12.2 moles of free oxygen atoms
Calculate the mass of beryllium (Be) needed to completely react with 18.9 g nitrogen gas (N2) to produce Bez N2, which is the only product of the reaction.
A. 6.19
B. 12.29
C. 18.29
D. 36.69
Answer:
C = 18.29 g
Explanation:
Given data:
Mass of beryllium needed = ?
Mass of nitrogen = 18.9 g
Solution:
Chemical equation:
3Be + N₂ → Be₃N₂
now we will calculate the number of moles of nitrogen:
Number of moles = mass/molar mass
Number of moles = 18.9 g/ 28 g/mol
Number of moles = 0.675 mol
Now we will compare the moles of nitrogen and Be from balance chemical equation.
N₂ : Be
1 : 3
0.675 : 3/1×0.675 = 2.03 mol
Number of moles of Be needed are 2.03 mol.
Mass of Beryllium:
Mass = number of moles × molar mass
Mass = 2.03 mol × 9.01 g/mol
Mass = 18.29 g
How do the percent compositions for C3H6 and C4H7 compare?
A. They are the same
B. C4H8 has a higher percentage of carbon than C3H6.
C. C4H8 has a higher percentage of hydrogen than C3H6.
D. none of the above
A. They are the same
Further explanationGiven
C3H6 and C4H8
Required
The percent compositions
Solution
C₃H₆(MW = 42 g/mol)%C = 3.12/42 x 100% = 85.71%
%H = 6.1/42 x 1005 = 14.29%
C₄H₈(MW=56 g/mol)
%C = 4.12/56 x 100% = 85.71%
%H = 8.1/56 x 100%=14.29%
So they are the same, because mol ratio of C and H in both compounds is the same, 1: 2
A solution was diluted 1/40, and the final concentration was 20%. What was the original concentration?
The original concentration : 800%
Further explanationGiven
Diluted 1/40
Final concentration 20%
Required
The original concentration
Solution
Dilution is the process of adding solvent to get a more dilute solution.
The moles(n) before and after dilution are the same.
Can be formulated :
n₁ = n₂
M₁.V₁ = M₂.V₂
diluted 1/40(dilution factor)⇒ V₁/V₂=1/40⇒V₂/V₁=40
M₂ = 0.2(20%)
Input the value for M₁ :
M₁=M₂ x (V₂/V₁)
M₁ = 0.2 x 40
M₂ = 8(800%)
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