Answer
B. When ΔH is negative and ΔS is positive
Explanation
The spontaneity of a reaction can be determined by the sign of the Gibbs free energy change. For a spontaneous reaction, the change in Gibbs free energy should be negative, that is:
[tex]\Delta G=\Delta H-T\Delta S[/tex]The spontaneity of a process can depend on the temperature. Since the temperature value here corresponds to the absolute temperature, this implies that T > 0 for any T. Therefore, to have a negative difference for any temperature value, the change in enthalpy (ΔH), should be negative and the change in entropy (ΔS) should be positive so that we always subtract a positive number from a negative number. This corresponds to a negative value in ΔG.
Hence, the
How many liters of NH3, at STP, will react with 5.3 g. O2 to form NO3 and water? 4NH3 (g) + 9O2 (g) —> 4NO3 + 6H2O (g)
Step 1
The reaction must be completed and balanced:
4NH3 (g) + 9O2 (g) => 4NO3 + 6H2O (g)
Reactants: NH3 and O2
Products: NO3 and H2O
--------------------
Step 2
Information provided:
STP conditions, therefore:
1 mole of gas (NH3 in this case) = 22.4 L (volume)
5.3 g of O2
Liters => L
Grams => g
---------
Information needed:
The molar mass of O2 = 32.0 g/mol
-------------------
Step 3
By stoichiometry,
1 mole NH3 = 22.4 L NH3
1 mole O2 = 32.0 g O2
Procedure: We will work with volume and mass
4NH3 (g) + 9O2 (g) => 4NO3 + 6H2O (g)
4 x 22.4 L NH3 ---------- 9 x 32.0 g O2
X ----------- 5.3 g O2
X = 5.3 g O2 x 4 x 22.4 L NH3/9 x 32.0 g O2 = 1.65 L approx.
Answer: 1.65 L of NH3
identify an element that has similar chemical properties as those of the element krypton (K).
Synthesize Information If you calculate the percent composition of elements in a compound, is there enough information to determine the empirical formula for the compound? If yes, how? If no, improve the model by identifying and explaining additional information needed to identify the compound.
If you only have the percent composition of each element in a give compound, you can't determine yet the empirical formular for the compound. The problem is, the percent composition only gives relative numbers for each element. What can be determined is the empirical stochiometry of one element relative to the others.
For example, supose you have a compound with element X and Y, with the percent composition you can determine how much X you have relative to how much Y you have. Say you determine that for each 2 X you have 3 Y, the formula can be X₂Y₃ but it can also be X₄Y₆ or even othre possibilities.
To determine the empirical formula you need to know how many of one of the elements you have in each compound. A common way of getting the empirical formula is to use the percent composition and, in addition, the molar mass of the compound, which will make it possible to get the empirical formula from the relative ratios of each element you have.
3.(a) Draw the following five-carbon hydrocarbons:•Pentane•Pentene•Pentyne(e)Classify each molecule and explain the differences between them. (Classes of organic molecules include alkanes, alkenes, alkynes, alcohols, carboxylic acids, aldehydes, ketones, esters, ethers, amines, and amides.)
Structural formulas are ways atoms and elements are arranged in a molecule. The structural formula of pentane, pentene, and pentyne are as shown below;
Pentane - C5H12
Pentene - C5H10
Pentyne - C5H8
e) Pentane is an alkane compound with a general formula CnH2n+2. The chemical formula of pentane is C5H12. There are only single bonds between the C-H atoms in the molecule.
Pentene is an alkene compound with a general formula of CnH2n. The chemical formula of pentene is C5H10. There is a double bond present between the C=H atoms. This double bond shows that the compound is an alkene.
Pentyne is an alkyne compound with a general formula of CnH2n-2. The chemical formula of pentene is C5H8. There is a triple bond present between the Carbon Hydrogen atoms. This presence of a triple bond shows that the molecule is an alkyne compound.
Abed found fingerprints at a crime scene that match fingerprints that were taken from the suspect. What does this MOST likely mean?
A.
The suspect’s fingerprints match someone else’s.
B.
All 150 ridge characteristics are identical.
C.
The suspect touched something at the crime scene.
D.
At least three different points were a perfect match.
Answer:
C
Explanation:
Because the suspect touched something at the crime scene and thus he's fingerprint are matching
6.5 grams of zinc reacted with hydrochloric acid. Calculate how many grams of hydrogen were released. a) 0.1 g. b) 0.2 g. c) 1.0 g. d) 2.0 g.
0.2 grams
ExplanationsThe balanced reaction between zinc and hydrochloric acid is given as:
[tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]Given the following parameters
Mass of Zinc = 6.5grams
Determine the mole of Zinc
Mole of Zn = mass/molar mass
Mole of Zn = 6.5/65.38
Mole of Zn = 0.0994moles
According to stoichiometry, 1 mole of Zinc produced 1 mole of hydrogen gas, hence the mole of hydrogen gas required will be 0.0994moles
Determine the mass of hydrogen gas produced
[tex]\begin{gathered} Mass\text{ of H}_2=mole\times molar\text{ mass} \\ Mass\text{ of H}_2=0.0944moles\times2.016 \\ Mass\text{ of H}_2=0.19g\approx0.2grams \end{gathered}[/tex]Hence the mass of hydrogen that were released is 0.2 grams
Question 7 of 10What makes up an ionic compound?O A. A positive cation and a negative anionB. A negative anion and a negative anionOC. A positive anion and a negative cationOD. A positive cation and a positive anionаSUBMIT
A ionic compound is made of two ions, one with positive charge and the other one with a negative charge.
The ion with positive charge is known as cation and the one with negative charge is known a anion.
It means that the correct answer is A. A positive cation and a negative anion.
What is the molarity of ions in a 0.561 M solution of Ca(OH)₂
assuming the compound dissociates completely?
For each particle (molecule) of Ca(OH)2 that was present, assuming full dissociation of the complex, you would get two particles (ions). CaO + H2O equals Ca(OH)2 (2 particles)
A 0.561 M solution contains 0.561 moles of Ca(OH)2 per kilogram of solvent. Ions' molality would be 2 x 0.561m = 1.122m.
How is an ion's molarity determined?The most used unit for expressing solution concentration is molarity (M), which is calculated by dividing the solute concentration in moles by the volume of the solution in liters: M stands for moles of solute per liter of solution.
What does ion molality mean?The kilograms of solvent divided by the moles of ions in the solution is the molality. As an illustration, if You will have 1.0 molal concentration of sodium chloride, for instance, if 1.0 moles of sodium chloride are dissolved in 1.0 kilogram of solution.
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A gas has a volume of 1.82 L at-30°C and 131 kPa. At what temperature would the gasoccupy 1.3 L at 233 kPa?Answer in units of°C.
To solve this problem we can use the Ideal gas law:
[tex]\frac{P_1\cdot V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]The problem give us de following information:
P1= 131kPa
V1=1.82L
T1=-30°C= 243.15 K
P2= 233 kPa
V2= 1.3L
Then we just have to solve for T2 and use the information provided:
[tex]T_2=\frac{P_2\cdot V_2}{P_1\cdot V_1}\cdot T_1=\frac{233\text{ kPa}\cdot1.3L}{131kPa\cdot1.82L}\cdot243.15K=308.91K=35.76°C[/tex]Then the answer is T2=35.76°C
A certain copper ore contains 3.24% of Cu2S by mass. In 1991, a single open-air smelt furnace heated 30000 tons of this ore. Compute the mass of copper metal obtained by this process. Enter in tons.
The mass of the copper that is obtained is 97.2 tons.
What is combustion?We can define the term combustion as the procedure by which a substance can be burnt in oxygen. We can also be able to refer to the process as roasting the object in the air. It is an oxidation reaction.
Having said all all of these, the reaction equation can be written as;
[tex]Cu_{2} S + O_{2} ------ > 2Cu + SO_{2}[/tex]
We know that the percent of the copper that it contains can now be used when we are trying to compute the mass of the copper that can be obtained from the process as we are going to have in the question that is at hand here to solve.
We are now going to proceed to see the mass of the copper that can be produced from the 300 tons of the copper I sulfide ore given.
Thus;
The mass of copper that can be obtained is;
3.24/100 * 3000 tons
= 97.2 tons
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True or false; The amount of energy required to heat 10 grams of water by 15 degreesCelsius is greater than that required to heat 10 grams of aluminum from15 degrees Celsius.
To answer this question we have to compare the specific heats of each substance.
The specific heat of a substance is the amount of energy required to make 1 gram of a substance increase its temperature by 1 °C. The greater the specific heat of a substance the more energy it will be required to heat it up.
The specific heat of water is 4.18J/g°C and the specific heat of aluminum is 0.897J/g°C.
It means that the amount of energy required to heat water is greater than the one to heat aluminum.
It means that the answer is TRUE.
Which of these are true situations that could be explained by the kinetic molecular theory?Select all that apply.
Kinect-molecular theory hypothesis:
- The formation of a gas occurs by a large number of molecules;
- Gas molecules have a negligible dimension, which means that the volume occupied by them is very small, almost insignificant;
- These gases move in a discontinuous and random way, thus occupying the entire volume of the container where they are found, having a rectilinear and uniformly varied movement;
- They are independent, they only interact with each other when a collision occurs;
- Collisions between molecules and molecules and between molecules and container walls are elastic collisions, which cause the kinetic energy of the molecules to remain constant.
Having seen these statements, the answers can only be:
The warmer a glass of water, the faster a drop of ink will spread through the water.
The colder a room is, the longer it would take to smell a spray of perfume from the other side of the room.
does lead melt in atoms or molecules
Answer:
Atoms
Explanation:
Answer:
atoms
Explanation:
its right, trust
A 695.7 ng sample of an unknown radioactive substance was placed in storage and its mass measured periodically. After 47 daysthe amount of radioactive substance had decreased to 86.96 ng. How many half-lives of the unknown radioactive substancehave occurred?
The decay of this radioactive unknown compound is a first-order process.
We can express the time dependence of its mass m using a first-order integrated rate law, where k is the rate constant:
[tex]m_t=m_0xe^{-kxt}[/tex]mt = mass at time t
m0 = initial mass
t = time
-----------------------------------------------------------------------------------------------------
Procedure:
1) We need to find "k":
From the first-order rate law we clear k,
[tex]\begin{gathered} \frac{m_t}{m_0}=\text{ }e^{-kxt} \\ \ln (\frac{m_t}{m_0})=\text{ -kxt} \\ \frac{\ln (\frac{m_t}{m_0})}{-t}=\text{ k} \end{gathered}[/tex][tex]k\text{ = }\frac{\ln (\frac{86.96ng}{695.7ng})}{-47}=0.044days^{-1}\text{ }[/tex]----------------------------------------------------------------------------------------------
2) We find the half-life from the value of k we have just calculated:
[tex]t_{\frac{1}{2}}=\text{ }\frac{\ln 2}{k}=\text{ }15.7\text{ days}[/tex]-----------------------------------------------------------------------------------------------
3) The number of half-lives of the unknown sample is:
Number of Half-lives = 47 days / 15.7 days = 3 (approx.)
Answer: Number of half-lives = 3
What is the percent yield if 15.5 g SO2 is obtained from the reaction of 42.5 g of O2 with excess ZNS according to the following equation 2ZnS (s) + 3O2 -> 2ZnO (s) + 2 SO2(g)
Answer:
Percent yield = 27.3%.
Explanation:
First, let's write the chemical equation:
[tex]2ZnS+3O_2\rightarrow2ZnO+2SO_2.[/tex]The limiting reactant, in this case, would be O2 because we have an excess of ZnS. So, we have to convert 42.5 g of O2 to moles. Remember that the molar mass of O2 is 32 g/mol (you can calculate the molar mass of a compound using the periodic table). The conversion will be:
[tex]42.5\text{ g O}_2\cdot\frac{1\text{ mol O}_2}{32\text{ g O}_2}=1.33\text{ moles O}_2.[/tex]With this value, we're going to find the number of moles of SO2 produced by 1.33 moles of O2. You can see in the chemical equation that 3 moles of O2 reacted produces 2 moles of SO2, so the calculation would look like this:
[tex]1.33\text{ moles O}_2\cdot\frac{2\text{ moles SO}_2}{3\text{ moles O}_2}=0.887\text{ moles SO}_2.[/tex]The next step is to find the mass of SO2 based on its number of moles and the molar mass of SO2 which is 64 g/mol, like this:
[tex]0.887\text{ moles SO}_2\cdot\frac{64\text{ g SO}_2}{1\text{ mol SO}_2}=56.8\text{ g SO}_2.[/tex]And finally, we replace the values that we have in the formula of percent yield:
[tex]\%\text{ yield }=\frac{experimental\text{ yield}}{theoretic\text{al yield}}\cdot100\%.[/tex]Our experimental yield is the mass that we obtained of SO2 which is 15.5 g and the theoretical yield is the mass that we found through stoichiometry which is 56.8g:
[tex]\%\text{ yield}=\frac{15.5\text{ g}}{56.8\text{ g}}\cdot100\%\approx27.3\%.[/tex]The percent yield of this reaction would be 27.3%
the partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. what is this attraction called?
Hydrogen bonding is formed when the partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule
Hydrogen bonding is a potent intermolecular force. In a water molecule, a partial negative charge is formed due to the oxygen, which is electro-negative.This oxygen gets attracted towards the positively charged Hydrogen, thus partial charges are shared between these two atoms of two different molecules.An electrostatic force is created between these molecules which helps in attraction of the partial charges.A hydrogen bond is formed between the water molecules which is formed due to hydrogen bonding. This kind of bond is formed between hydrogen atom and an electronegative atom, typically fluorine (F), nitrogen (N), or oxygen (O).Thus, when the partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule, hydrogen bonding is formed.
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If I have 10.0g of Mg, what is my theoretical yield of MgCl2
Explanation:
First, let's write the balanced equation of formation of MgCl2 from Mg and Cl2:
Mg + Cl2 → MgCl2
Now let's transform 10.0g of Mg into moles, using the following formula: moles = mass/molar mass
molar mass of Mg = 24.3 g/mol
moles = 10/24.3
moles = 0.412 moles
Now we use the equation ratio between Mg and MgCl2 to find the quantity of MgCl2 in moles.
1 mole of Mg produces 1 mole of MgCl2.
So 0.412 moles of Mg produces 0.412 moles of MgCl2.
Now we transform 0.412 moles of MgCl2 into mass using the following formula: mass = moles x molar mass
Molar mass of MgCl2: 24.3 + (2*35.45) = 95.21 g/mol
Mass = 0.412 * 95.21
Mass = 39.2 g
Answer: The theoretical yield of MgCl2 is 39.2 g.
What makes water a polar molecule? options:A) The equal forces between oxygen and hydrogenB) The liquid nature of waterC) The uneven bend in the bond between oxygen and hydrogenD) The ionic bond between oxygen and hydrogen
The polarity of a molecule is given by the difference in charges, hydrogen has a slightly positive charge and oxygen has a negative charge. Its electronegativity difference between hydrogen and oxygen is less than 1.7 making the bond a covalent bond.
That said, we can rule out options A and D. Now, the state of matter does not affect the polarity of the molecule, so option B will also be incorrect.
The correct option will be C, since there is a difference in charges that makes water polar.
Answer: C) The uneven bend in the bond between oxygen and hydrogen
Classify each of the following chemical reactions as a synthesis decomposition and single displacement or double displacement reaction
1. Synthesis reaction : there is only 1 product formed from 2 or more reactant
E.g:
[tex]H_2(g)+N_2(g)\text{ }\Rightarrow2NH_3(g)\text{ }[/tex]2. Decomposition : reaction that occurs in presence of UV light and only 1 reactant that decomposes into 2 or more products.
E.g:
[tex]CH_3Br(g)+UV_{light}\Rightarrow CH_3(g)\text{ + Br (g)}[/tex]3. Single displacement : reaction that occurs when 1 reactant displaces other reactant from its compound:
E.g:
[tex]Zn(s)+CoCl_2(aq)\text{ }\Rightarrow ZnCl_2(aq)\text{ + Co(s)}[/tex]4. Double displacement : reaction that occurs when both reactant displaces each other.
E.g :
[tex]K_2S(aq)+Co(NO_3)_2\Rightarrow2KNO_3(aq)\text{ + }CoS(s)\text{ }[/tex]Consider the balanced thermochemical equation given below: W(s) + 3 H2O(g) → WO3(s) + 3 H2(g) ∆Η° = –125.9 kJ How many grams of H2 were produced when 377 kJ of heat was produced?
Answer:
Explanation:Consider the balanced thermochemical equation given below: AH = -125.9 kJ W(s) + 3 H2O(g) WO3(s) + 3 H2(g) If a mass of 94.6 g H2 is produced, what is the enthalpy change? Express your answer in kJ. Express your answer to the correct number of significant figure, in scientific notation and include the unit with
Calculate the mass (in g) of 5.86x10^20 SO3 molecules.
Answer
0.0779 g SO₃
Procedure
To solve this question, you will need to use the Avogadro's number equivalent to 6.02214 x 10^23 molecules/ mol, and then the molecular weight in grams per mole for the SO₃.
[tex]5.86\times10^{20}\text{ molecules SO}_3\frac{1\text{ mol SO}_3}{6.02214\text{ x 10}^{23}\text{molecules SO}_3}\frac{80.06\text{ g SO}_3}{1\text{ mol SO}_3}=0.0779\text{ g SO}_3[/tex]I need help with filling out the cubes and emery’s, basically the Application: Assigning Oxidation numbers (shown in the photo)
According to the explanation about oxidizing and reducing agents from the previous session, we will find the answers to this question as well
Oxidation numbers are mostly found in previously made tables, there are plenty of tables where you can see the oxidation numbers for almost every element, a few rules to have in mind is H is usually +1, O is -2, Halogens are -1, group 1A metals are +1, transition metals are the ones that will shift a lot
1. Sn + 2 HCl -> SnCl2 + H2, this is the properly balanced equation
REACTANTS
Sn = 0, since it's a lone element in the reaction we assume its charge is 0 because is stable
H = +1
Cl = -1, it's a halogen
PRODUCTS
Sn = +2, we see now that Sn was oxidized and now has a positive charge
Cl = still -1
H2 = 0, was reduced, now with a 0 charge
2. 2 NaBr + Cl2 -> 2 NaCl + Br2
REACTANTS
Na = +1, metal from group 1A
Br = -1, halogen
Cl2 = 0 stable element
PRODUCTS
Na = +1
Cl = -1, it will be reduced
Br = 0, it will be oxidized
3. SiCl4 + 2 Mg -> 2 MgCl2 + Si
REACTANTS
Si = +4
Cl = -1
Mg = 0
PRODUCTS
Mg = +2, it will be oxidized
Cl = -1
Si = 0, it will be reduced
How many copper atoms are in a pure copper statue with a mass of 187 kg?
Avogadro's number states that:
1 mol of Cu = 63.54 g of Cu = 6.02x10^23 atoms of Cu
Now, we proceed like this:
1 kg = 1000 g ===> 187 kg = 187,000 g
63.54 g Cu -------- 6.02x10^23 atoms of Cu
187,000 g Cu -------- X
X = 1.77x10^27 atoms Cu
Answer: 1.77x10^27 atoms Cu
Which of the following elements would have chemical properties similar to those of Na?O Ne KBr
Ne is a noble gas, O is a non metal and Br is an halogen.
K is a metal that belongs to the same group as Na, it means that they have similar chemical properties.
It means that the answer is K.
Create a table of different types of radioactive decay and the changes that result in each.
answer and explanation
Radioactivity is the emission of ionizing radiation from nuclear decay. there are three types of radioactive decay.
alpha decay
in alpha decay an alpha particle is released. In the parent atom, the atomic number decreases by 2 and the atomic mass decreases by 4
beta decay
in beta decay a beta particle is released, the atomic number is unchanged and the atomic mass increases by 1
gamma decay
in gamma decay, energy is released as gamma rays from an excited nuclear state. the atomic mass and atomic number remain unchanged.
12: from the following list, decide whether the following are Arrhenius bases or acids.•HCl•NaOh•HBr•H2SO4•NH4OH•H3PO4•HNO3•LiOH•Ba(OH)2•CsOH•HF•KOH
Answer:
The Arrhenius acids in the list are:
HCl, HBr , H2SO4 , H3PO4 , HNO3 , HF
The Arrhenius bases are:
NaOH , NH4OH , LiOH , Ba(OH)2 , CsOH and KOH
Explanation:
An Arrhenius acid increases the concentration of H+ ions while an Arrhenius acid increases the concentration of OH- ions
Thus, an Arrhenius acid would yield H+ ions on ionization while an Arrhenius base will yield OH- ions on ionization
The Arrhenius acids in the list are:
HCl, HBr , H2SO4 , H3PO4 , HNO3 , HF
The Arrhenius bases are:
NaOH , NH4OH , LiOH , Ba(OH)2 , CsOH and KOH
a sample of a gas is at STP and it’s temperature remains constant. if the pressure decreases what will happen to the volume
Explanation
There are said to have two different conditions of a gas.
First condition is STP which means: pressure = 1 atm and temperature (absolute) = 0 °C + 273 = 273 K
-------------
It is said that the temperature remains constant, therefore we can apply Boyle's law which states that the pressure of a gas tends to decrease as the volume of the container increases.
How many moles of carbon dioxide are formed when reacting with 36 moles of oxygen?
1) Chemical equation
[tex]CH_4+2O_2\rightarrow CO_2+2H_2O[/tex]2) Moles of CO2 produced oxygen reacts
The molar ratio
2 mol O2: 1 mol CO2
[tex]molCO_2_{}=36molO_2\cdot\frac{1molCO_2}{2molO_2}=18molCO_2[/tex]If 36 mol O2 reacts, it will produce 18 mol CO2.
.
Calculate the number of moles of magnesium, chlorine, and oxygen atoms in 8.30 moles of magnesium perchlorate,Mg(Cl04)2Express the number of moles of Mg, Cl, and O atoms numerically, separated by commas.moles of Mg, CI, O =
The question requires us to calculate the number of moles of each element (magnesium, chlorine and oxygen) in 8.30 moles of the compound magnesium perchlorate (Mg(ClO4)2).
From the molecular formula of magnesium perchlorate we can take the following information:
- in 1 mol of Mg(ClO4)2, there is only 1 mol of Mg;
- in 1 mol of Mg(ClO4)2, there are 2 moles of Cl;
- in 1 mol of Mg(ClO4)2, there are 8 moles of O.
With the information above, and knowing that the amount of Mg(ClO4)2 given by the question was 8.30 moles, we can calculate the amount, in moles, of each element:
1 mol Mg(ClO4)2 --------------- 1 mol Mg
8.30 mol Mg(ClO4)2 ---------- x = 8.30 mol Mg
1 mol Mg(ClO4)2 --------------- 2 mol Cl
8.30 mol Mg(ClO4)2 ---------- y = 2 x 8.30 mol Cl = 16.6 mol Cl
1 mol Mg(ClO4)2 --------------- 8 mol O
8.30 mol Mg(ClO4)2 ---------- z = 8 x 8.30 mol O = 66.4 mol O
Therefore, there are 8.30, 16.6 and 66.4 moles of Mg, Cl and O in 8.30 moles of magnesium perssufate.
Potential Molecular TheoryThere are 500 grams of Kl in a volumetric flask. It is dissolved in 1 liter of water. What is the molarity?3.141 M3.012 M0.500 M500.000 M20A precipitate is formed when two solutions are mixed. This would only occur if
Molarity or molar concentration is a measure of the concentration of a chemical species, of a solute in a solution, using as units, number of moles, and volume in liters. The formula for Molarity is:
M = n/V
Where:
n = number of moles
V = volume in Liters, 1 Liter
But we need to find the number of moles, we will do so by using its molar mass, KI = 166g/mol and the given mass in the question, 500g grams
166g = 1 mol
500g = x moles
x = 3.012 moles
Now we can use the Molarity formula
M = 3.012/1
M = 3.012 M, this is the molar concentration of the solution, 2