Heating to constant mass is done to retain the constant mass of the sample so that its weight remains the same and does not affect the reading throughout the experiment.
Heating to constant mass is a process in which a sample usually a powder or crystal is heated until the mass of the sample remains constant or the same.This is done to remove the excess moisture or other impurities that may affect the accuracy of the readings during the experiment.In this process, the sample is heated, cooled down weighed, and again the sample is heated, cooled down, and weighed. This process is done repeatedly until the mass of the sample remains constant in two or three consecutive measurements. Thus, heating to constant mass gives a minimized error during the experiment.To learn more about how the mass number is calculated for an element click below:
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During her presentation, Zahara was asked several questions from the audience and to provide the molecular formula for molecules that the audience had questions about. Help Zahara show the molecular formula for the following compounds: Trisilicon tetranitride
Because tri means 3, there are 3 silicon atoms, and tetra means 4, so there will be 4 nitrogen atoms, the answer is:
[tex]_{N_4Si_{3_{}}}[/tex]A popular car has an engine that is reported to have a volume of 5840 . What is the size in cubic inches?
By using an appropriate conversion factor, the size of this popular car's engine is equal to 356.78 cubic inches.
What is a conversion factor?A conversion factor simply refers to a number that is typically used to convert a number in one (1) set of units to another, either by dividing or multiplying.
Generally speaking, an appropriate conversion factor to an equal value must be used when it is necessary to perform any mathematical conversion.
Conversion:
1 cubic centimeter = 0.061023744094732 cubic inches.
5,840 cubic centimeter = X cubic inches.
Cross-multiplying, we have:
X = 0.061023744094732 × 5,840
X = 356.78 cubic inches.
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Complete Question:
A popular car has an engine that is reported to have a volume of 5840 cm³. What is the size in cubic inches?
What is the energy of a purple
lamp with a frequency of
7.5 x 10^14 Hz
Answer:
[tex] \huge{4.969 \times {10}^{ - 19} \:J }[/tex]
Explanation:
The energy of the purple lamp can be found by using the formula
E = hf
where
E is the energy
f is the frequency
h is the Planck's constant which is
6.626 × 10-³⁴ Js
From the question.
[tex] f = 7.5 \times 10^14 \: Hz [/tex]
We have.
[tex] E = 6.626 \times 10^{-34} \times 7.5 \times 10^{14} [/tex]
We have the final answer as
[tex]4.969 \times {10}^{ - 19} \: J[/tex]
The volume of ammonia gas at .930 atm of pressure is gradually decreased from 96.2mL to 44.7mL. What is the final pressure of ammonia if there is no change in temperature?
Initial Pressure = P₁ = 0.930 atm
Final Pressure = P₂ = ?
Initial Volume = V₁= 96.2 mL
Final Volume = V₂ = 44.7 mL
Temperature = constant
If we consider that ammonia as an Ideal Gas, and since the temperature is constant we can apply Boyle's Law. It says that at constant temperature:
P₁ * V₁ = P₂ * V₂
If we divide at both sides by V₂:
P₁* V₁ / V₂ = P₂ * V₂ / V₂
On the right side we can cancel V₂ and we get:
P₁* V₁ / V₂ = P₂
P₂ = P₁* V₁ / V₂
Replacing by the values that we were given:
P2 = 0.930 atm * 96.2 mL / (44.7 mL)
P2 = 2.00 atm
So the final pressure is 2.00 atm
A scientist uses a graduated cylinder to measure 100.0 mL of gasoline for an experiment. The density of gasoline is 0.774 g/mL. What is the mass of this gasoline sample?
Answer:
100ml x 0.774
divide by 4
x by 8
Which is the least electronegative element?Group of answer choicescarbonnitrogenoxygenaluminum
In order to solve this question, we can use the electronegativity table (or also just a regular periodic table), which will give us the values of electronegativity for each element.
As we can see in this table, the least electronegative element will be Al, with only 1.61 of value. If you were with a regular periodic table, you could find this answer by thinking about the periodic table trend, or we can also call it a rule, that in most elements the electronegativity will grow in value from left to right and from the bottom to the top, then you would also get Al as your answer
Answer = Al, letter D
Which of the following statements about temperature scales are correct? Select all that apply.
Zero on the Kelvin scale corresponds to absolute zero.
The Kelvin and Fahrenheit scales are commonly used in chemistry.
The units the Celsius and Fahrenheit scales are both called degrees.
Water boils at 273 K on the Kelvin scale.
Zero on the Kelvin scale corresponds to absolute zero this statements about temperature scales is correct
What is Temperature scales ?Using a beginning point (0 or zero) and a unit of measurement, a temperature scale can be used to indicate or measure temperature. This is typically accomplished by designating certain physical events as occurring at 0 and 100 degrees Fahrenheit, respectively, at specific temperatures, such as the freezing and boiling points of water.
The Fahrenheit and Celsius (Centigrade) systems are the two most often used temperature scales. Due to the fact that all molecular activity stops at the zero points of the Rankin and Kelvin scales, two other scales, they are known as the absolute scales. This location is referred to as absolute zero.Learn more about Temperature scales here:
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asap
compare and contrast chemical and physical equilibrium
Answer:
The difference between chemical and physical equilibrium. Physical is a reversible change of state. Chemical is a reversible chemical reaction that can go in the direction to create products or to create reactants.
A physical equilibrium is an equilibrium state in which the physical state of the system does not change. Chemical equilibrium is the equilibrium state in which the concentrations of reactants and products is not changed with time.
Hope this helps!
What type of bond is formed between hydrogen and oxygen atoms within a water molecule?Ionic bondNonpolar covalent bondPolar covalent bondHydrogen bondWhich of the following best describes a solute that is dissolved in water?Aqueous solutionGaseous solutionAlloyHeterogeneous solution
To determine what type of bond is formed when hydrogen and oxygen form water, we have to find the difference in electronegativities of hydrogen and oxygen:
[tex]3.44-2.2=1.24[/tex]According to this, the difference between electronegativities is less than 1.7 and greater than 0.4, which means that the type of bond formed by oxygen and hydrogen is polar covalent bond.
Consider this reaction:3Ca(s)+2H3PO4(aq)=Ca3(PO4)2(s)+3H2(g)How many grams of calcium are required to produce 50.500 g of calcium phosphate (MW = 310.19g/mol) assuming an excess of Phosphoric acid?
Answer
19.6 grams
Explanation
Given:
Mass of calcium phosphate produced = 50.500 g
Equation: 3Ca(s) + 2H3PO4(aq) ---> Ca3(PO4)2(s) + 3H2(g)
What to find:
The grams of calcium required to produce 50.500 g of calcium phosphate.
Step-by-step solution:
From the equation, 3 mol Ca produce 1 mol Ca3(PO4)2
1 mole Ca3(PO4)2 = 310.19 grams
1 mole Ca = 40.078 grams
This means, (3 x 40.078 g) = 120.234 g Ca produce 310.19 g Ca3(PO4)2
So x grams Ca will be required to produce 50.500 grams Ca3(PO4)2
x grams Ca will be equal
[tex]\frac{50.500\text{ }g}{310.19\text{ }g}\times120.234g\text{ }Ca=19.6\text{ }grams\text{ }Ca[/tex]The grams of calcium required to produce 50.500 g of calcium phosphate = 19.6 grams
A testable question is, “How does the amount of exercise affect heart rate and breathing rate?” Which is a controlled variable?O Amount of exerciseO Heart rateO Breathing rateO Temperature in the room
Answer
Temperature of the room
Explanation
The room temperature can be controlled compared to all other options.
During a titration, an endpoint was reached after adding 20 mL of sodium hydroxide solution, NaOH(aq), to 20 mL of sulfuric acid, H2SO4. The sodium hydroxide solution had a concentration of 1.50 mol/L. What was the initial concentration of the sulfuric acid? Select one: a. 1.50 mol/L b. 2.25 mol/L c. 3 mol/L d. 0.75 mol/L
Write the balanced chemical equation for the reaction as follows:
[tex]2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O[/tex]Given:
Concentration of sodium hydroxide =1.50 mol/L
Volume of sodium hydroxide = 20 mL
Concentration of sulfuric acid = x
Volume of sulfuric acid = 20 mL
Firstly, we will determine the moles that is in 20 mL of 1.5 M NaOH:
[tex]\begin{gathered} 1.5\text{ }mole=1000mL \\ x\text{ }mol=20mL \\ \\ x=\frac{1.5mol\times20mL}{1000mL} \\ \\ x=0.03mol\text{ }NaOH \end{gathered}[/tex]Based on the balanced chemical equation and the moles of NaOH we can use stoichiometry (ratios) to determine the moles of 20 mL sulfuric acid:
[tex]0.03mol\text{ }NaOH\times\frac{1mol\text{ }H_2SO_4}{2mol\text{ }NaOH}=0.015\text{ }mol[/tex]Now that we know how many moles are in 20 mL of H2SO4, we can determine the moles in 1000mL (initial concentration):
[tex]\begin{gathered} 0.015\text{ }mol=20\text{ }mL \\ x\text{ }mol=1000\text{ }mL \\ x=\frac{0.015mol\times1000mL}{20mL} \\ \\ x=0.75mol•L^{-1} \end{gathered}[/tex]Answer: D) 0.75 mol/L,
what are terms used for solubility or concentration expression ?
Answer:
The correct expression used for solubility is a. grams per 100 grams of solvent. One of the most commonly used methods for expressing the concentrations is molarity.
Complete the balanced dissociation equation for the compound below. If
the compound does not dissociate, write NR after the reaction arrow.
LiOH(s) →
LiOH ⇌ Li + + OH - NR
When there are too many OH ions, water dissociates fully to the left, possibly leaving only Li + and OH ions and H 2 O molecules.
IN CHEMISTRY, WHAT IS AN ION?An atom or collection of atoms that is classified as an ion as a different number of electrons than proton atoms. The particle is a positive ion, also known as a cation, if the number of electrons is smaller than the number of protons.
How do ions form?Ions are created when there are more protons in an atom than electrons, which is the case in all atoms. An atom that has gained or lost one or more electrons, and as a result has a negative or positive charge, is what is referred to as an ion. Exchanging electrons between atoms or molecules is the process of ionization.
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What is the limiting reactant if 43.4 g of NH3 react with 30 g of NO? The balanced equation is 4NH3 + 6NO --> 5N2 + 6H2O
Answer
NO is the limiting reactant
Explanation
Given that:
The mass of NH3 that reacted = 43.4 g
The mass of NO that reacted = 30 g
The equation for the reaction is: 4NH3 + 6NO --> 5N2 + 6H2O
What to find:
The limiting reactant.
Step-by-step solution:
The first step is to convert the given mass of the reactants to moles.
Using the mole formula and the molar masses of (NH3 = 17.0 g/mol and NO = 30.0 g/mol)
[tex]\begin{gathered} Moles=\frac{Mass}{Molar\text{ }mass} \\ \\ Moles\text{ }of\text{ }NH_3=\frac{43.4g}{17.031g\text{/}mol}=2.55\text{ }mol \\ \\ Moles\text{ }of\text{ }NO=\frac{30g}{30.0g\text{/}mol}=1.0\text{ }mol \end{gathered}[/tex]The final step is to determine the limiting reactant by comparing the mole ratio from the given equation with the mole ratio in the step above.
From the equation, 4 moles of NH3 reacted with 6 moles of NO
So 2.55 moles of NH3 is expected to react with (2.55 x 6)/4 = 3.825 moles of NO
1.0 mol NO is less than 3.825 mol NO, hence, NO is the limiting reactant because it will be the reactant to be completely used up first.
What is the mass in grams of 8 moles of ammonia, NH3?
The first step to find the mass of the 8 moles of NH₃ is to find the molar mass of NH₃. The molar mass of any compound is the mass of one mol of it. To calculate it, we have to look for the atomic masses of the elements that the molecule has.
N: 14.01 amu
H: 1.01 amu
Then the molar mass of NH₃ will be:
molar mass of NH₃ = 14.01 + 3 * 1.01
molar mass of NH₃ = 17.04 g/mol
Now that we know the molar mass of NH₃ (the mass of one mol of it) we can easily find the mass of 8 moles.
mass = 8 moles of NH₃ * 17.04 g/mol = 136.32 g
mass = 136.32 g
Answer: the mass in grams of 8 moles of ammonia is 136.32 g
The following lists consists of ionic compounds EXCEPT
barium hydroxide, zinc carbonate, ammonium sulfate
calcium chloride, carbon disulfide, magnesium nitrate
sodium sulfate, copper(II) oxide, potassium nitride
aluminium sulfide, sodium sulfite, calcium fluoride
Except for NACLE, the is made up of ionic compounds. Carbon disulfide bonds are not ionic due to their weak and trivial polarity. Carbon disulfide bonds are covalent due to the small difference in electronegativities of carbon and sulfur.
What makes an ionic bond?Ionic bond, also known as electrovalent bond, is a type of linkage formed in a chemical compound by the electrostatic attraction of oppositely charged ions. When the valence (outermost) electrons of one atom are permanently transferred to another, a bond is formed.After two or more atoms lose or gain electrons to form an ion, an ionic bond can form. Ionic bonds form when metals lose electrons and nonmetals gain electrons. Ions with opposite charges attract each other, forming an ionic bond.To learn more about Ionic Bond, refer to:
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identify the functional group and name the compound ch3ch2ch2ch2ch2ch2cho
Answer: valeraldehyde
Explanation:
I had to memorize this one
The functional group present is aldehyde and name of compound is valeraldehyde.
What are functional groups?Functional group is defined as a substituent or group of toms or an atom which causes chemical reactions.Each functional group will react similarly regardless to the parent carbon chain to which it is attached.This helps in prediction of chemical reactions.
The reactivity of functional group can be enhanced by making modifications in the functional group .Atoms present in functional groups are linked to each other by means of covalent bonds.They are named along with organic compounds according to IUPAC nomenclature.
Functional group inter conversion is also possible by retro -synthesis.In some cases , functional groups can be charged molecules.
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What is known about the first forensic laboratory?
A.
It was opened by the Los Angeles Police Department.
B.
It was started by the Federal Bureau of Investigation.
C.
It opened in the late 1800s.
D.
It was built by a Chinese emperor in the 1200s.
Answer:
It was started by the FBI
What's the difference between ionization and dissociation?
Question options:
A)
Ionization breaks ionic bonds, and dissociation breaks covalent bonds.
B)
Ionization involves complete breakdown, while dissociation is only partial.
C)
Ionization breaks covalent bonds, and dissociation breaks ionic bonds.
The difference between ionization and dissociation : Ionization breaks ionic bonds, and dissociation breaks covalent bonds.
Ionization breaks the ionic bond into its constituent ions while dissociation is breaking of bond into its simple constituent. Ionization is a irreversible process and dissociation is reversible process. The bond involves in the process of ionization is ionic bond and the bond involved in the process of dissociation is the covalent bond. The compound related to ionization is ionic compound and the compounds related with dissociation is covalent compound.
Thus, The difference between ionization and dissociation :
(A) Ionization breaks ionic bonds, and dissociation breaks covalent bonds.
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Calculate the energy and frequency of red light having a wavelength of 650 nm (Note => 650 nm = 6.50 * 10^7 m)
The energy and frequency of the red light would be 2.88 × 10⁻¹⁹ Joules and 4.615 × 10¹⁴ Hz respectively if the red light has a wavelength of 650
nm.
What is Wavelength?It can be understood in terms of the distance between any two similar successive points across any wave for example wavelength can be calculated by measuring the distance between any two successive crests.
C = λν
As given in the problem we have to calculate the energy of the light if the wavelength of light is 6.5 × 10⁻⁷ meters.
The frequency of the red light = 3 × 10⁸ / 6.5 × 10⁻⁷
= 4.615 × 10¹⁴ Hz
The energy of the red light = h ν
= 6.26 × 10⁻³⁴ × 4.615 × 10¹⁴
= 2.88 × 10⁻¹⁹ Joules
Thus, the energy and frequency of the red light would be 2.88 × 10⁻¹⁹ Joules and 4.615 × 10¹⁴ Hz respectively.
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QUESTION 2How many grams of NaOH are present in 27.0 mL of a 2 M solution?
We want the mass of NaOH, Given:
V = 27.0 mL = 0.0270 L
C = 2 M
Given the concentration and volume we can find the number of moles of NaOH, and then convert it to mass.
C = n/V (or Molarity = moles of solute/litres of the solution) where C is the concentration or molarity, n is the number of moles of the solute and V is the volume of the solution
n = Cv
n = 2 x 0.0270 L
n = 0.054 mol
Now that we have the number of moles, we can get the mass of NaOH. Molar mass of NaOH = 39,997 g/mol
n = m/M where m is the mass and M is the molar mass
m = nM
m = 0.054 mol x 39,997 g/mol
m = 2.16 g
When copper is heated with an excess of sulfur, copper(I) sulfide is formed.
In a given experiment, 1.53 g of copper was heated with excess sulfur to yield 1.76 g of copper(I) sulfide.
What is the percent yield?
If 1.53 g of copper is heated with excess sulfur to yield 1.76 g of copper (I) sulfide, the percent yield would be 75.43%.
Percent yieldThe percent yield of a reaction is the actual yield relative to the theoretical yield of the same reaction.
The percent yield of a reaction is mathematically expressed as:
Percent yield = actual yield/theoretical yield x 100%.
Let us now consider the reaction in question. The equation of the reaction is given as:
[tex]Cu + S --- > CuS[/tex]
The mole ratio of the copper that reacts to the copper sulfide that is formed is 1:1.
Recall that: mole = mass/molar mass
The molar weight of copper is 63.55 g/mol
Mole of 1.53 g copper = 1.53/63.55
= 0.024 moles
The equivalent mole of copper sulfide produced will also be 0.024 moles.
The molar mass of CuS is 95.61 g/mol
Mass of 0.024 moles CuS = 0.024 x 96.61
= 2.32 g
2.32 g is the theoretical yield of the reaction. But 1.76 g of copper sulfide is the actual yield.
Percent yield = 1.75/2.32 x 100%
= 75.43%
Thus, the percent yield of the reaction, if 1.53 g of copper is heated with excess sulfur to produce 1.76 g of copper (I) sulfide, is 75.43%.
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How many atoms are in this compound: Li₂SO₂?
To count atoms, we can find the total sum of the subscripts in a chemical compound.
This is the case for most compounds. In some cases, we will have to multiply subscripts when there are elements inside brackets.
Solving the QuestionWe're given:
Li₂SO₂
In front of lithium (Li), there is a 2.
In front of sulfur (S), there is nothing, which means 1.
In front of oxygen (O), there is a 2.
Add:
2 + 1 + 2 = 5
Therefore, there are 5 atoms in Li₂SO₂.
Answer5 atoms
I need your help with this question
No need explaining just say the answer thanks
Answer: CHOCH
The third one
Explanation:
10) Identify the substance as an acid or a base and put an "X" in the box.
l
Identify the substance as an acid or a base and put an "X" in the box lemon juice is the acid sodium hydroxide is the base and ammonia is the weak base and HCl is the strong acid
An acid is the any hydrogen containing substances that is capable of donating a proton to another substances and base is the molecule or ion able to accept a hydrogen ion from acid and acidic substances are usually identified by their sour taste and here given example are lemon juice acidic because they contain high amount of citric acid and sodium hydroxide is the base because they dissociate completely into the solution to form hydroxide ion and ammonia is the weak base because nitrogen atom has electron pair that easily accept a proton and HCl is the strong acid because it dissociate almost completely
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Recall the postulates of kinetic-molecular theory. Read the list and check all the statements that apply to the behavior of an ideal gas:1. gas particles behave like hard spheres2. gas particles travel randomly3. gas particles are attracted to each other4. energy is lost when gas particles collide 5. average kinetic energy of a collection of gas particles depends on the temperature6. gas particles occupy most of the space within a container7. gas particles have mass and volume
Answer:
Chemistry - States of matter - Kinetic Molecular Theory
This is the theory that explains the states of the matter and is based on the idea that matter is composed of tiny particles that are always on motion.
Part 1: Check all the statements that apply to the behavior of an ideal gas
The behaviors that apply are:
1.Gas paarticles behave like hard sphares.
2.Gas particles travel randomly.
5. Average kinetic energy of a collection of gas particles depends on the temperature.
Part 2: According to kinetic-molecular theory the one that would not be considered an ideal gas is:
A gas with highly polar molecules that have very strong intermolecular forces.
This is because the theory consideres thhat there are no forces of attraction of repultion between gas particles.
How many moles are there in 2.50 grams of ethanol, C2H6O ?
Where are the alkali metals and the alkaline earth metals located? How do the characteristic properties of each group compare/contrast to the other?
Alkali Metals are located in the first group in the periodic table. (Hydrogen is not alkali, be careful with that).
Alkaline Earth Metals are in group number two, right next to the Alkali Metals.
You have to look at the vertical groups ( 1 and 2).
----------------------------------------------------------------------------------------------------------------
ALKALI METALS (AL) VS ALKALINE EARTH METALS (ALE).
Alkali Metals are soft, Alkaline Earth Metals are hard.
AL have only one electron in the last shell, ALE have 2.
AL present a low melting point, ALE high.
AL form hydroxides strongly basic, ALE hydroxides are less basic.
AL are more reactive than ALE
AL have +1 ionic charge in their compounds, ALE have +2 ionic charge in their compounds.
How many grams of fluorine gas occupy 543.2ml and exert 123456 pa of pressure at 29.8 degrees Celsius
Answer:
m = 506 grams of fluorine
Explanation:
Given:
M = 19·10⁻³ kg / mol - molar mass of fluorine
V = 543.2 mL = 543.2·10⁻³ m³
p = 123456 Pa
t = 29.8°C
_____________________
m - ?
Temperature in degrees Kelvin:
T = 273.15 + t = 273.15 + 29.8 = 302.95 K
Clapeyron-Mendeleev law:
p·V = (m/M)·R·T
Mass of fluorine:
m = p·V·M / (R·T)
m = 123456·543.2·10⁻³·19·10⁻³ / (8,31·302.95) ≈ 0.506 kg
or m = 506 g