CHEMICAL CALCULATIONS HOMEWORK

1. A chemical formula includes the symbols of the elements in the compound and sub-
scripts that indicate
a. atomic mass of each element. c. formula mass.
b. number of atoms or ions of each element d. charges on the elements or ions.
O that are combined in the compound.

2. A chemical formula for a molecular compound represents the composition of

O
a. a molecule. c. the ions that make up the com-
pound.
b. an atom. d. the crystal lattice.

3. The formula for carbon dioxide, CO2, can represent

a. one molecule of carbon dioxide. atoms of oxygen.
b. 1 mol of carbon dioxide molecules.
c. the combination of 1 atom of carbon and 2 O d. all of the above.

4. The molar mass of an element is the mass of one

a. atom of the element. c. gram of the element.
b. crystal of the element. d. mole of the element.
O in grams
5. What is the sum of the atomic masses of all the atoms in a formula for a compound?
a. molecular mass c. atomic mass
b. formula mass d. actual mass
0 6. What is the formula mass of magnesium chloride, MgCl2?
a. 46 amu
b. 59.76 amu O
c. 95.21 amu
d. 106.35 amu

7. What is the formula mass of ethyl alcohol, C 2H5OH?

a. 30.33 amu c. 45.06 amu
b. 33.27 amu d. 46.08 amu

8.
O
What is the formula mass of (NH4)2SO4?
a. 114.09 amu c. 128.06 amu
b. 118.34 amu d. 132.16 amu

9. The molar mass of MgI2 is

O
O
a. the sum of the masses of 1 mol of Mg and 2
mol of I.
c. the sum of the masses of 1 atom of Mg and
2 atoms of I.
b. the sum of the masses of 1 mol of Mg and 1 d. the sum of the masses of 1 atom of Mg and
mol of I. 1 atom of I.

10. The molar mass of NO2 is 46.01 g/mol. How many moles of NO2 are present in 114.95
g?
a. 0.4003 mol
b. 1.000 mol Oc. 2.498 mol
d. 114.95 mol
 11. The molar mass of CCl4 is 153.81 g/mol. How many grams of CCl4 are needed to have
5.000 mol?
a. 5 g c. 769.0 g
b. 30.76 g O
d. 796.05 g

12. The molar mass of H2O is 18.02 g/mol. How many grams of H2O are present in 0.20
mol?
a. 0.2 g c. 35.9 g

O
b. 3.6 g d. 89.9 g

13. The molar mass of LiF is 25.94 g/mol. How many moles of LiF are present in 10.37 g?

O
a. 0.3998 mol
b. 1.333 mol
c. 2.500 mol
d. 36.32 mol

14. The molar mass of CS2 is 76.15 g/mol. How many grams of CS2 are present in 10.00
mol?
a. 0.13 g c. 10.00 g
b. 7.614 g d. 761.5 g

15.
O
The molar mass of NH3 is 17.03 g/mol. How many moles of NH 3 are present in 107.1 g?
a. 0.1623 mol
b. 3.614 mol Oc. 6.289 mol
d. 107.1 mol

16. What is the mass of 0.240 mol glucose, C 6H12O6?

a. 24.0 g c. 180.16 g
b. 43.2 g d. 750. g
O
17. How many Cl– ions are present in 2.00 mol of KCl?

O
a. 1.20 1024 c. 2.00
b. 6.02 1024 d. 0.5

18. How many OH– ions are present in 3.00 mol of Ca(OH)2?
a. 3.00
b. 6.00 O
c. 3.61 1024
d. 2.06 1023

19. How many oxygen atoms are there in 0.500 mol of CO 2?

a. 6.02 1023 c. 15.9994
b. 3.01 10 d. 11.0
O
23

20. How many Mg2+ ions are found in 1.00 mol of MgO?
a. 3.01 1023 c. 12.04 1023

O
b. 6.02 10 23 d. 6.02 1025

21. If 0.500 mol of Na+ combines with 0.500 mol of Cl– to form NaCl, how many formula
units of NaCl are present?
O
a. 3.01 1023
b. 6.02 1023
c. 6.02 1024
d. 1
O
22. How many molecules are there in 5.0 g of methyl alcohol, CH 3OH?
a. 9.4 10 22 c. 3.6 1024
b. 3.0 1024 d. 3.8 1024

23. What is the percentage composition of CF 4?

a. 20% C, 80% F c. 16.8% C, 83.2% F
O
b. 13.6% C, 86.4% F d. 81% C, 19% F

24. What is the percentage composition of CO?

a. 50% C, 50% O c. 25% C, 75% O
b. 12% C, 88% O d. 43% C, 57% O

25.
O
What is the percentage composition of CuCl 2?
a. 33% Cu, 66% Cl c. 65.50% Cu, 34.50% Cl
b. 50% Cu, 50% Cl
O
d. 47.27% Cu, 52.73% Cl

26. The percentage composition of sulfur in SO 2 is about 50%. What is the percentage of
oxygen in this compound?
a. 25% c. 75%

O
b. 50%

27.
d. 90%

What is the mass percentage of OH– in Ca(OH)2?

O
a. 45.9%
b. 66.6%
c. 75%
d. 90.1%

28. What is the mass percentage of chlorine in NaCl?

a. 35.45% c. 60.7%
b. 50% O
d. 64.5%

29. What follows an element’s symbol in a chemical formula to indicate the number of at-
oms of that element in one molecule of the compound?
a. charge sign c. number in parentheses
b. superscripted number
O
d. subscripted number

30. The formula mass of any compound is described in units of

a. grams. c. moles.
b. amu. d. grams per mole.
O 31. The molar mass of water is equal to
a. 1 g of O plus 2 g of H. mol of H.
b. 1 g of O plus 1 g of H. d. the mass of 1 mol of O plus the mass of 2
c. the mass of 1 mol of O plus the mass of 1
O mol of H.

32. What is the molar mass of pure tin?

a. 1.00 g/mol
b. 47.88 g/mol O
c. 118.71 g/mol
d. 237.42 g/mol
 33. How many moles of compound are there in 15.0 g of potassium dichromate, K 2Cr2O7?
(The molar mass of K2Cr2O7 is 294.2 g.)
a. 0.0510 mol c. 15.0 mol
b. 11.0 mol d. 294 mol

34. What is the mass percentage of cobalt in cobalt(II) fluoride, CoF 2?

a. 33.33%
b. 39.20% Oc. 60.80%
d. 96.93%

35. What is the mass of 4.80 mol of barium hydride, BaH 2?

a. 4.80 g c. 139 g
b. 29.0 g
O
d. 669 g

36. How many atoms are present in one formula unit of barium acetate, Ba(C 2H3O2)2?
a. 4
b. 8
O
c. 15
d. 16

37. The mass of a molecule is found by

O
a. adding the masses of all the atoms in the
molecule.
c. multiplying the total mass of all the atoms
in the molecule by 6.022 x 1023.
b. dividing the total mass of all the atoms in d. dividing the total mass of all the atoms in
the molecule by 6.022 x 1023. the molecule by the total number of atoms.

38. For any molecule, formula unit, or ion, the sum of the average atomic masses of all the
atoms represented in a formula is the
O
a. formula mass.
b. ionic mass.
c. molecular mass.
d. atomic mass.

39. What is the correct formula mass for zinc hydroxide, Zn(OH) 2?
a. 83.41 g c. 83.41 amu
b. 99.41 g

40.
O
One mole of potassium atoms has a mass of
d. 99.41 amu

a. 1 g. c. 78.20 g.
b. 39.10 g. d. 6.022 x 1023 g.
O 41. A compound’s molar mass is numerically equal to
a. the total number of atoms in the molecule. c. its mass number.

O
b. the total number of moles of the compound. d. its formula mass.

42. How many total moles of atoms are there in one mole of silver(I) phosphate, Ag PO ?
3 4

O
a. 3 c. 8
b. 7 d. 11

43. What is the correct molar mass of Ag 3PO4?

a. 418.58 g/mol c. 154.84 g/mol
O
b. 387.61 g/mol d. 52.32 g/mol
 44. Which statement shows how to correctly convert from the mass of a compound in

0
grams to the amount of that compound in moles?
a. c.
molar mass (g/mol) x = amount mass (grams) x =
(moles) amount (moles)
b. molar mass (g/mol) x 6.022 x 1023 = amount d. mass (grams) x molar mass (g/mol) =
(moles) amount (moles)

45. The percentage composition of a compound is

a. the percentage by volume of each element mass of each element in 1 mol of the com-
in the compound. pound.
b. the percentage by mass of each element in d. the mass of each element in 1 mol of the
O the compound.
c. the molar mass of the compound the
compound x the molar mass of the com-
pound.

46. What is the percentage of iron in iron(III) chloride, FeCl3? The molar mass of FeCl3 is
162.2 g/mol.
a. 25.00% c. 61.17%
b. 34.43% d. 65.57%
O
Use the table of atomic masses to answer the following questions. Write your answer below, and
show your work in the space provided.

Element Symbol Atomic Element Symbol Atomic

mass mass
Aluminum Al 26.98 amu Lead Pb 207.2 amu
Bromine Br 79.90 amu Lithium Li 6.94 amu
Carbon C 12.01 amu Magnesium Mg 24.30 amu
Chlorine Cl 35.45 amu Manganese Mn 54.94 amu
Chromium Cr 52.00 amu Nitrogen N 14.01 amu
Copper Cu 63.55 amu Oxygen O 16.00 amu
Fluorine F 19.00 amu Sodium Na 22.99 amu
Hydrogen H 1.01 amu Sulfur S 32.07 amu

1. What is the molar mass of tetraethyl lead, Pb(C 2H5)4?

323,3 glnot
2. What is the formula mass of copper(II) chloride, CuCl 2?

134.45 glad
3. What is the percentage composition of CuCl 2 by mass?
 47.29 copper 52.71 chlorine
4. What is the mass of 0.240 mol glucose, C 6H12O6?

43,29
…end of homework