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- 1. Multiple Choice
What is the percent of oxygen by mass in a pure sample of sodium nitrate?
13%
56%
18%
28%
- 2. Multiple Choice
The molar mass of potassium fluoride, KF, is 58.1g/mol
The molar mass of potassium carbonate, K2CO3, is 138.2g/mol
The molar mass of potassium nitrate, KNO3, is 101.3g/mol
Which of the following shows the correct percent by mass?
I) KF, 67% potassium
II) K2CO3 28% potassium
III) KNO3 39% potassium
I, II, and III
II and III only
I and III only
III only
- 3. Multiple ChoiceA substance has a molar mass of 60 g/mol with 40.0 percent carbon, 6.7 percent hydrogen, and 53.3 percent oxygen. What is its empirical formula?C2H4O2C2H2O4CHO2CH2O
- 4. Multiple ChoiceAn elemental analysis of compound X shows that the mass percentage composition of the compound is 26.86% C and 2.239% H, with the remainder being oxygen. A mass spectrum of X yields a molar mass of 90.0 g/mol. Write the molecular formula of X.CHO2C2H2O4C2H2OCH2O
- 5. Multiple ChoiceA hydrocarbon (an organic compound containing only C and H) is found to be 7.74% H. If the molecular weight is known to be between 70 and 85 amu, find the molecular formula.C6H10C5H12C6H12C6H6
- 6. Multiple Choice
Which of the following could NOT be an empirical formula.
CH4
CH
C2H6
CH6
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