Chemistry spring final exam review
How many moles of aluminum are needed to react completely with 1.2 mol of FeO? 2Al(s) + 3FeO(s) --> 3Fe(s) + Al2O3(s)
0.80 mol
How many moles of H3PO4 are produced when 71.0 g P4O10 reacts completely to form H3PO4? P4O10(s) + 6H2O(l) --> 4H3PO4(aq)
1.00 mol
How many molecules are there in 2.10 mol CO2?
1.26 × 10^24 molecules
What is the number of moles in 432 g of barium nitrate, Ba(NO3)2?
1.65 mol
How many moles of glucose, C6H12O6, can be "burned biologically when 10.0 mol of oxygen is available? C6H12O6(s) + 6O2(g) --> 6CO2(g) + 6H2O(l)
1.67 mol
What is the molarity of 200 mL of solution in which 206 g of sodium bromide, NaBr, is dissolved?
10M
What is the volume of alcohol present in 200.0 mL of a 55% by volume solution of alcohol?
110 mL
What is the percent by volume of 400.0 g of a solution that contains 60.0 g of calcium chloride, CaCl2?
15.0%
How many grams of beryllium are needed to produce 36.0 g of hydrogen? Be(s) + 2H2O(l) --> Be(OH)2(aq) + H2(g)
161 g
How many moles of oxygen gas would be needed to react with 155 g of propane gas, C3H8, in a combustion reaction? C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(l)
17.6 mol
What is the molarity of a solution containing 9.0 moles of solute in 500.0 mL of solution?
18 M
The equation below shows the decomposition of lead(II) nitrate. How many grams of oxygen are produced when 11.5 g NO2 is formed? 2Pb(NO3)2(s) --> 2PbO(s) +4NO2(g) + O2(g)
2.00 g
How many atoms are there in 3.5 moles of arsenic atoms?
2.1 × 10^24 atoms
What is the percent composition of chromium in BaCrO4?
20.5%
Sodium thiosulfate, Na2S2O3, is used as a fixer when developing photgraphic film. What is the mass in grams of Na2S2O3 needed to make 100.0 mL of a 0.250 M solution?
250 M= x/.1 x= .025 mols .025 mols x 156 g /mol= 3.9 g
What volume in liters of a 2.5 M solution of acetic acid, CH3COOH, is needed to provide 256 g of acetic acid?
256 g / 60 g/mol = 4.27 mol CH3COOH 2.5 M = 4.27 mol / x 2.5 x = 4.27 x = 1.71 L
Given the following balanced chemical equation, N2 + 3H2 --> 2NH3, what is the mole ratio for calculating moles of hydrogen from moles of nitrogen?
3 mol H2 / 1 mol N2
What is the molar mass of gold(III) chloride (AuCl3)?
303.6 g/mol
What mass of sucrose, C12H22O11, is needed to make 500.0 mL of a 0.200 M solution?
34.2 g
What is the molar mass of chromium (III) sulfate, Cr2(SO4)3?
392.2 g/mol
How many moles of helium atoms are there in 2.4 × 1024 helium atoms?
4.0 mol
What is the number of moles of beryllium atoms in 36 g of Be?
4.0 mol
Calculate the molarity of 4.65 mol NaOH dissolving in 5.0 L of solution.
4.65 mol/5L= 0.93M
Iron is generally produced from iron ore through the following reaction in a blast furnace. If 400 g of Fe2O3 are available to react, how many moles of CO are needed? Fe2O3 + 3CO →2Fe + 3CO
400 g Fe2O3 x 1 mol Fe2O3/159.6 g Fe2O3 x 1 mol CO/ 1 mol Fe2O3= 1200/159.6= 7.518 mol CO
Phosphorus burns in air to produce a phosphorus oxide in the following reaction. What mass of phosphorus will be needed to produce 3.25 mol of P4O10? 4P + 5O2 --> P4O10
403 g
What is the mass in grams of 5.90 moles of octane, C8H18
673 g
The chemical formula of aspirin is C9H8O4. What is the mass of 0.40 mol of aspirin?
72g
What is the percent composition of carbon in heptane, C7H16?
84%
How many molecules of water are produced when 1.0 mole of NO2 is produced according to the following balanced chemical equation? 4NH3(g) + 7O2(g) --> 4NO2(g) + 6H2O(g)
9.0 x 10^23 molecules
What numerical value does 6.02 × 10 ^23represent?
A) Avogadro's number
Which of the following would be expected to dissolve very readily in water? A) NaOH B) H2 C) CH4 D) CBr4
A) NaOH
Which of the following statements explains why ionic substances are soluble in water? A) Water molecules are polar. B) Water is a covalent substance. C) An oxygen atom has six valence electrons. D) The molar mass of water is 18.02 g/mol.
A) Water molecules are polar.
Mole ratios for a reaction are obtained from the A) balanced chemical equation B) total mass of products C) molar masses D) periodic table
A) balanced chemical equation
In general, as the temperature of a solution composed of a gas in a liquid is increased, the solubility of the gas A) decreases B) increases C) remains the same
A) decreases
The lowest whole-number ratio of the elements in a compound is called the _____. A) empirical formula B) binary formula C) representative formula D) ionic compound E) molecular formula
A) empirical formula
When two substances react to form products, the reactant which is used up is called the _____. A) limiting reactant B) determining reactant C) excess reactant D) catalytic reactant
A) limiting reactant
Calculate the mass of silver chloride, AgCl, formed when 85.6 g of silver sulfide, Ag2S, reacts with excess hydrochloric acid, HCl, to produce silver chloride and hydrogen sulfide. Ag2S + 2HCl →2AgCl + H2S
Ag: 2(107.9) S: 32.1 MM: 247.9 Ag : 107.9 Cl: 35.5 MM: 143.4 85.6 g Ag2S x 1 mol Ag2S/247.9 g Ag2S x 2 mol AgCl/ 1 Ag2S x 143.4 g AgCl/ 1 mol AgCl 24550.08/247.9= 99.03 g AgCl
Which of the following is NOT an empirical formula? A) MoO2Cl2 B) C2N2H8 C) C3H8O D) Sb2S3 E) BeCr2O7
B) C2N2H8
A mole of potassium chloride (KCl) contains 6.02 × 1023 _____. A) molecules KCl B) formula units KCl C) ions KCl D) atoms KCl
B) formula units KCl
Which of the following solutes is most effective in lowering the vapor pressur of water? A) MgCl2 B) NaCl C) AlCl3 D) CCl4
C) AlCl3
What is the first step in solving any stoichiometric problem? A) Determine the molar amount of the known substance using mass-to-mole conversion. B) Determine the molar amount of the unknown substance from the molar amountof the known substance using mole-to-mole conversion. C) Balance the chemical equation representing the reaction. D) Determine the mass of the unknown stubstance using mole-to-mass conversion
C) Balance the chemical equation representing the reaction.
What SI unit is used to measure the number of representative particles in a substance? Question options: A) kelvin B) kilogram C) mole D) ampere
C) mole
A burning candle can be extinguished by using a snuffer, which consists of a small, metal cone on a long handle. What reactant does the snuffer limit when used to extinguish the candle? A) the candle B) carbon dioxide C) oxygen D) water vapor
C) oxygen
What is the empirical formula of a substance that is 53.5% C, 15.5% H, and 31.1 %N by weight?
C2H7N
What is the molecular formula for a compound that is 46.16% carbon, 5.16 % hydrogen and 48.68% fluorine if the molar mass of this compound is 156.12 g/mol?
C6H8F4
Which of the following compounds have the same empirical formula? A) CO2 and SO2 B) C6H12 and C6H14 C) C4H10 and C10H4 D) C7H14 and C10H20 E) NO and NO2
D) C7H14 and C10H20
A mole ratio is _____. A) a fraction B) a conversion factor C) a ratio D) all of the above
D) all of the above
Which among the following is an electrolyte? A) Mg(NO3)2 B) NH4OH C) KCl D) all of these E) none of these
D) all of these
When two substances react to form products, the reactant which is left over is called the _____. A) limiting reactant B) determining reactant C) catalytic reactant D) excess reactant
D) excess reactant
In a chemical reaction, the mass of the products _____. A) has no relationship to the mass of the reactants B) is less than the mass of the reactants C) is greater than the mass of the reactants D) is equal to the mass of the reactants
D) is equal to the mass of the reactants
All of the following are equal to Avogadro's number EXCEPT _____. A) the number of formula units of sodium phosphate in 1 mol Na3PO4 B) the number of atoms of gold in 1 mol Au C) the number of molecules of nitrogen in 1 mol N2 D) the number of atoms of bromine in 1 mol Br2
D) the number of atoms of bromine in 1 mol Br2
In a spacecraft, the carbon dioxide exhaled by astronauts can be removed by its reaction with lithium hydroxide, LiOH, according to the following chemical equation. How many moles of lithium hydroxide are required to react with 20 moles of CO2, the average amount exhaled by a person each day? CO2 + 2LiOH --> Li2CO3 + H2O
Known: 20 mol CO2 Unknown: Mol LiOH 20 mol CO2 x 2 mol LiOH/ 1 mol CO2 40 mol LiOH
In a spacecraft, the carbon dioxide exhaled by astronauts can be removed by its reaction with lithium hydroxide, LiOH, according to the following chemical equation. How many moles of lithium hydroxide are required to react with 20 moles of CO2, the average amount exhaled by a person each day? CO2 + 2LiOH equation Li2CO3 + H2O
Known: 20 mol of CO2 Unknown: mol of LiOH 20 mol CO2 x 2 mol LiOH/1 mol CO2= 40 mol LiOH
Table salt, sodium chloride, is produced from its elements through a synthesis reaction. What mass of chlorine would be required to produce 25.0 mol of sodium chloride? 2Na + Cl2 --> 2NaCl
Known: 25 mol NaCl Unknown: g Cl 25 mol NaCl x 1 mol Cl2/ 2 mol NaCl x 70.906 g Cl2/ 1 mol Cl = 1772.65/2= 886.325 g Cl2
If 4.50 mol of ethane, C2H6, undergo combustion according to the equation below, how many moles of oxygen are required? 2C2H6 + 7O2 →4CO2 + 6H2O
Known: 4.50 mol C2H6 Unknown: mol of O 4.50 mol C2H6 x 7 mol O/ 2 mol C2H6 = 31.5/2 = 15.75 mol of O
If 4.50 mol of ethane, C2H6, undergo combustion according to the equation below, how many moles of oxygen are required? 2C2H6 + 7O2 → 4CO2 + 6H2O
Known: 4.50 mol of ethane Unknown: mol of oxygen 4.50 mol C2H6 x 7 mol oxygen/2 mol C2H6 31.5/2=15.75 mol oxygen
Calculate the mass of silver chloride, AgCl, formed when 85.6 g of silver sulfide, Ag2S, reacts with excess hydrochloric acid, HCl, to produce silver chloride and hydrogen sulfide. Ag2S + 2HCl -->2AgCl + H2S
Known: 85.6 g Ag2S Unknown: mass of AgCl 85.6 Ag2S x 1mol Ag2s/ 247.802 g Ag2S x 2 mol AgCl/ 1 Ag2S x 143.4g AgCl/ 1 mol Ag Cl= 24550.08/247.802=99.071 g AgCl
Avogadro's number of representative particles is equal to one _____.
Mole
What is the empirical formula of a compound that is 40% sulfur and 60% oxygen?
SO3
Mr. Harry's new baby is sick and not nursing well. The doctor suggests Pedialyte which is a dilute sugar solution along with vitamin C. If there are 25 grams of dextrose dissolved in 1000 g of solution, what is the percent concentration?
Solute-25 g dextrose Solvent- Solution-1000 g 25g/1000 x 100= 2.5%
What is the general rule for dissolving?
The general rule for dissolving is that polar dissolves polar and nonpolar dissolves nonpolar. Also, temperature is a big factor as well, certain elements dissolve with hotter temperatures and some dissolve with colder temperatures such as gas.
Which of the following operations usually makes a substance dissolve faster in a solvent? A) raising the temperature B) crushing the substance to a powder C) agitation D) all of the above
all of the above
Why does a solute depress the freezing point?
because the solute disrupts crystal formation by the solvent
physical property that depends on the number of particles a solute yields in solution
colligative property
solution containing a large amount of solution
concentrated solution
measure of the amount of solute dissolved in a specified quantity of solvent
concentration
solution containing a small amount of solute
dilute solution
describes liquids that are insoluble in one another
immiscible
Iron is generally produced from iron ore through the following reaction in a blast furnace. If 400 g of Fe2O3 are available to react, how many moles of CO are needed? Fe2O3 + 3CO-->2Fe + 3CO2
known: 400 g Fe2O3 unknown: moles CO 400 g Fe2O3 x 1 mol Fe2O3/ 159.69 g Fe2O3 x 3 mol CO/ 1 mol Fe2O3 1200/ 159.69 = 7.515
Stoichiometry is based on the law of conservation of _____.
mass
describes liquids that are soluble in one another
miscible
The mass in grams of one mole of any pure substance is known as _____
molar mass
number of moles of solute dissolved in 1 L of solution
molarity
Table salt, sodium chloride, is produced from its elements through a synthesis reaction. What mass of chlorine would be required to produce 25.0 mol of sodium chloride? 2Na + Cl2 →2NaCl
mole-mass Known: 25.0 mol NaCl Unknown: g Cl2 25.0 mol NaCl x 1 mol Cl/2 mol NaCl x 71 g Cl2/ 1 mol Cl = 1775/2= 887.5 g Cl2
A formula that specifies the actual number of atoms of each element in one molecule of a compound is called a ____
molecular formula
Bromine, Br2, is _____ and it will dissolve best in ____
nonpolar oil
Which of the following would be expected to dissolve readily in the nonpolar solvent CCl4? A) Ca(OH)2 B) KNO3 C) table salt D) oil
oil
Polar solvents will dissolve ______ solutes
polar
Table sugar, C12H22O11, is _____ and it will dissolve best in ___
polar water
solution containing maximum amount of solute
saturated solution
A 4.0 g sugar cube is dissolved in a teacup containing 350 g of water. What is the percent by mass of the sugar solution?
sol- 4 g sugar solv- 350 g solution- 354 g 4/354 x 100 = 1.13 %
What mass of water must be added to 250 g NaCl to make a 15 percent by mass aqueous solution?
sol-250 g solv-? solution- 1666.67 250/x x 100= 15 250/x= 15/100 250/x= .15 250= .15x x= 250/.15 x=1666.67 solvent= 1666.67-250g= 1416.67
Which of the following is NOT a colligative property of a solution? A) solubility B) boiling-point elevation C) vapor-pressure lowering D) freezing-point depression
solubility
How does the solubility of a solid generally vary as the temperature increases?
solubility increases
The process of surrounding solute particles with solvent particles to form a solution is called __
solvation
If salt is dissolved in water, water serves as the ___
solvent
The calculation of quantities in chemical equations is called ___
stoichiometry
If a crystal added to an aqueous solution causes many particles to come out of the solution, the original solution was ___
supersaturated
solution containing more solte than can theoretically dissolve at a given temperature
supersaturated solution
solution containing less than the maximum amount of dissolved solute
unsaturated solution
What is the molarity of a potassium chloride solution that has a volume of 400.0 mL and contains 85.0 g of KCl?
volume = .4L 85 g KCl x 1 mol/74.551 g KCl= 1.14 mol 1.14 mol/.4L= 2.85M
_____ is the universal solvent because it is ____
water polar
A solution of ammonia (NH3) contains 6.0% NH3 by volume. How many milliliters of NH3 are in 28 mL of the solution?
x/28 x 100= 6% x/28= 6/100 x= .06 (28) x= 1.68