TTU General Chemistry

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Chem 111 - Quiz 2D - Fall, 1997
Chapter II: Chemical Formulas and Compound Stoichiometry

1. Which of the following statements is incorrect?

a) A molecule is the smallest part of a compound that can have a stable independent existence.
b) Molecules that consist of more than one atom are called polyatomic molecules.
c) The atomic number of an element is defined as the number of neutrons in the nucleus.
d) Molecules of compounds are composed of more than one kind of atom.
e) The charge on an electron is negative and the charge on a proton is positive.

2. Calculate the number of moles of nitrogen atoms in 20.9 grams of nitrogen.

a) 1.49 moles
b) 0.746 moles
c) 0.37 moles
d) 1.74 moles
e) 1.23 moles

3. Calculate the formula weight of K3PO4.

a) 173.2 amu
b) 134.1 amu
c) 212.3 amu
d) 228.3 amu
e) 185.1 amu

4. What is the mass of 2.50 moles of CH3CH2OH?

a) 100 g
b) 102 g
c) 46.0 g
d) 115 g
e) 239 g

5. What is the mass of 1.0 x 1012 molecules of O2?

a) 1.9 x 1013 g
b) 6.0 x 1011 g
c) 2.7 x 10-11 g
d) 5.3 x 10-11 g
e) 1.7 x 10-12 g

6. Suppose you have a 100 gram sample of each of the following compounds. Which sample contains the smallest number of moles of compound?

a) NH3
b) MgCl2
c) H3PO4
d) CrCl3
e) NaCl

7. Calculate the percent by mass of nitrogen in ammonium carbonate, (NH4)2CO3.

a) 14.5%
b) 27.8%
c) 29.2%
d) 33.3%
e) 17.1%

8. A 4.628 g sample of an oxide of iron was found to contain 3.348 g of iron and 1.280 g of oxygen. What is the simplest formula for this compound?

a) FeO
b) Fe2O3
c) Fe3O4
d) FeO2
e) none of these answers

9. Balance the following equation with the smallest whole number coefficients. Choose the answer that is the sum of the coefficients in the balanced equation. Do not forget coefficients of one. P4 + Cl2 --> PCl5

a) 7
b) 9
c) 11
d) 13
e) 15

10. Balance the following equation with the smallest whole number coefficients. Choose the answer that is the sum of the coefficients in the balanced equation. Do not forget coefficients of one. C7H16 + O2 --> CO2 + H2O

a) 23
b) 27
c) 29
d) 30
e) 32

11. How many moles of CO2 would be produced from 56 moles of O2 according to the following balanced equation? 2C2H6 + 7O2 --> CO2 + H2O

a) 16
b) 32
c) 224
d) 48
e) 8

12. The complete combustion of a hydrocarbon produced 352 mg of CO2 and 216 mg of H2O. What is the simplest formula of this hydrocarbon?

a) CH
b) CH2
c) C2H3
d) CH3
e) C3H2

13. Which of the following statements is not an idea from Daltonıs Atomic Theory?

a) An element is composed of extremely small indivisible particles called atoms.
b) All atoms of a given element have identical properties which differ from those of all other elements.
c) Atoms can only be transformed into atoms of another element by nuclear reactions.
d) Compounds are formed when atoms of different elements combine with each other in small whole-number ratios.
e) The relative numbers and kind of atoms are consistent in a given compound.

14. What is the molecular formula for ammonia?

a) HNO3
b) HNO2
c) NH3
d) CH4
e) N2H4

15. Consider the following balanced equation. 2H2 + O2 --> 2H2O Which one of the following statements is false?

a) One molecule of O2 will react with 2 molecules of H2.
b) One mole of O2 will react with 2 moles of H2.
c) The complete reaction of 32.0 g of O2 will produce 2 moles of H2O.
d) The complete reaction of 2.0 g of H2 will produce 36.0 g of H2O.
e) The amount of reaction that consumes 32.0 of g O2 produces of 36.0 g H2O.

KEY

1)c 2)a 3)c 4)d 5)d 6)d 7)c 8)c 9)e 10)b 11)b 12)d 13)c 14)c 15)d