Chapter 7 Review

1
Chapter 7 Review

• Honors Theoretical Chemistry

2
Writing Formulas

• Iron(II) phosphate
• Copper(II) sulfate
• Calcium phosphate
• Aluminum hydroxide
• Nitric acid
• Sulfuric acid

• Fe3(PO4)2
• CuSO4
• Ca3(PO4)2
• Al(OH)3
• HNO3
• H2SO4

3
Naming Formulas

• P2O5
• SO3
• CCl4
• CuCl2
• Na2S
• SrO
• CH4

• Diphosphorus pentaoxide
• Sulfur trioxide
• Carbon tetrachloride
• Copper (II) chloride
• Sodium sulfide
• Strontium oxide
• methane

4
Hydrates are (choose all that apply)

• Salts
• Ionic compounds
• Wet to touch

5

• How many moles of ions are in 72 g of Al(NO3)3?
• Which has more ions, 0.40 g of NaOH or 0.10 moles
  of BaCl2?

1.4 moles of ions
BaCl2
6
You have 16.5 g of oxalic acid, H2C2O4 which has
a molar mass of 90.04 g/mol.

• How many moles of oxalic acid are represented?
• How many molecules of oxalic acid are present?
• How many atoms are carbon do you have?

0.183 moles
1.10 x 1023 molecules
2.20 x 1023 atoms C
7

• What percent, by mass of the compound caffeine,
  C8H10N2O2 is carbon?
• What is the mass percent of nitrogen in NH3?

57.8
82.4
8
The mineral ilmenite, FeTiO3, is a source of
titanium.

• What is the percent titanium in ilmenite?
• What mass of ilmenite, in grams, is required if
  you wish to obtain 750 grams of titanium?

31.6
2370 g
9
Eugenol is the major component in oil of cloves.

• What is the empirical formula of eugenol? The
  compound contains 73.14 C and 7.37 H and 19.49
  O by mass.

C5H6O
10

• Solid tin metal and solid, purple iodine react to
  form orange, solid tin iodide with an unknown
  formula. If 0.455 g Sn reacts with 1.947 g
  iodine, what is the empirical formula of tin
  iodide?

SnI4
11

• A gallium oxide forms when gallium is combined
  with oxygen. If 1.25 g gallium reacts to form
  1.68 grams of gallium oxide, what is the
  empirical formula of the product?

Ga2O3
12

• Capsaicin, the compound that gives the hot taste
  to chili peppers, has the formula C18H27NO3.
  Its molar mass is 305.46 g/mol.
• If you eat 55 mg of capsaicin, how many moles
  have you consumed?
• Calculate the mass percent of C in capsaicin.

1.8 X 10-4 moles
70.8 C
13
Give empirical formulas

• P6N6Cl12
• Al2(SO4)3
• Na2O2
• Ta2O6
• Sr2C2O4
• Mo2S5
• Co4P2O8

• P1N1Cl6
• Al2(SO4)3
• Na1O1
• Ta1O3
• Sr1C1O2
• Mo2S5
• Co2P1O4

14

• A chemist obtains a sample of an unknown
  compound which is 43.6 phosphorus and 56.4
  oxygen its molecular weight falls between 250
  and 300 grams per mole. Determine both the
  empirical and molecular formulas for the
  compound.

Empirical P2O5 Molecular P4O10
15

• Which of these has the greatest nitrogen by
  mass?
• NH3
• C(CN)2
• NH4OH
• N2H4

16
Find formulas for these hydrates

• 0.737 g MgSO3 and 0.763 g H2O
• 89.2 BaBr2 and 10.8 H2O.
• 0.391 g Li2SiF6 and 0.0903 g H2O
• 76.9 CaSO3 and 23.1 H2O

MgSO3 6H2O
BaBr2 2H2O
Li2SiF6 2H2O
CaSO3 2H2O
17

• A compound has the empirical formula CHOCl with
  a molar mass of approximately 130 g/mol.
  Determine the molecular formula.
• A compound contains 1.6 g Cerium and 4.54 g
  Iodine. Write the empirical formula

C2H2O2Cl2
CeI3
18

• 12.0 g of Na2CO3 is used as a source of sodium.
  What is the theoretical percent of Na in the
  compound?
• What mass of sodium should be recovered from the
  120 g sample?
• 3.16 g Na is actually recovered. What is the
  percent yield?

43.4
5.20 g
60.7
19
Students react CuSO4 with iron in the lab and
gather the following data

•  Mass CuSO4 (159.6 g/mol) 2.04 g
• Mass Fe 0.70 g
• Mass filter paper 1.32 g
• Mass filter paper and Cu 1.99 g
• Mass of Cu _____
•  Based on these results what percent of CuSO4 is
  copper?
• What is the theoretical yield of copper that the
  students should have gotten?
• Determine their percent yield.

0.67 g Cu 32.8 39.8 82.6 yield
20

• A crucible has a mass of 40.00 g when empty and
  48.02 g after hydrated sodium carbonate is added.
  The crucible is heated to drive off the water
  then cooled and weighed. The final mass is 44.42
  g.
• How many moles of water were contained in the
  original sample of hydrated sodium carbonate?
• How many moles of sodium carbonate were contained
  in the original sample of hydrated sodium
  carbonate?
• c) What is the formula of hydrated sodium
  carbonate?

o.200 moles water 0.0417 moles
Na2CO3 Na2CO3 14 H2O
21

• Hydrate used CuWO4 ___ H2O
• mass of empty crucible 18.546 g
• mass of crucible plus hydrate 20.832 g
• mass of hydrate used  ________
• mass after heating 20.596 g
• mass of anhydrous salt left behind ________
• moles of anhydrous salt left behind ________
• mass of water driven off ________
• moles of water driven off ________
• mole ratio of anhydrous salt to water ________
• formula of hydrate ________

CuWO4 2 H2O
22
Naming Formulas

• C2H6
• C4H10
• Ba(OH)2
• (NH4)2CO3
• Mg3(PO4)2
• HC2H3O2
• FeS
• Fe2O3

• Ethane
• Butane
• Barium hydroxide
• Ammonium carbonate
• Magnesium phosphate
• Acetic acid
• Iron(II) sulfide
• Iron(III) oxide