TTU General Chemistry

----

Chem 111 - Quiz 2A - Fall, 1996
Chapter II: Chemical Formulas and Composition Stoichiometry

1. Identify the compound below which is an ionic compound.

a) CH4
b) H2O2
c) Na2CO3
d) NH3
e) SO2

2. Identify the compound formula that is INCORRECT.

a) Ca3(PO4)2 for calcium phosphate
b) NaNO3 for sodium nitrate
c) K2CO3 for potassium carbonate
d) NH4SO4 for ammonium sulfate
e) KCl for potassium chloride

3. Identify the INCORRECT statement below:

a) The atomic weight is the number of atoms in one mole of the element.
b) The electron and proton have charges of equal magnitude and opposite sign.
c) The atomic number is the number of protons in the nucleus.
d) An atom is the smallest particle of an element that maintains the chemical identity of that element.
e) The number above the element symbol on the periodic chart is the atomic number.

4. Identify the INCORRECT statement below:

a) Atoms cannot be created, destroyed, or transformed into atoms of another element except by nuclear reactions.
b) Some elements exist in pure form as polyatomic molecules.
c) All atoms of a given element have identical properties, which differ from those of other elements.
d) Compounds form when masses of different elements combine in small whole-number ratios.
e) The relative numbers and kinds of atoms are constant in a given compound.

5. How many Hydrogen atoms are present in 27.0 g of H2O?

a) 1.80 x 1024
b) 9.03 x 1023
c) 6.02 x 1023
d) 27.0
e) 4.5 x 10-23

6. Calculate the formula weight of TNT, trinitrotoluene, which has a formula C6H2(CH3)(NO3)3.

a) 179
b) 263
c) 247
d) 307
e) 275

7. Calculate the % Oxygen in NaHCO3, sodium bicarbonate.

a) 57.1%
b) 43.3%
c) 19.0%
d) 0.57%
e) 21.7%

8. Determine the simplest empirical formula of a compound with the following composition by mass: 29.1% Na; 40.5% S; 30.4 % O.

a) NaSO2
b) Na2S2O3
c) NaSO3
d) Na2SO4
e) Na2SO3

9. An alkene hydrocarbon with an empirical formula of CH2 has a molecular weight of 98.2 amu. What is the true molecular formula for the compound?

a) CH2
b) C7H14
c) C8H2
d) C3H6
e) C5H10

10. How many grams of Nitrogen combine exactly with 6.0 grams of Hydrogen to produce NH3?

a) 7.0 g
b) 2.0 g
c) 14.0 g
d) 28.0 g
e) 1.28 g

11. Balance the following chemical equation with the smallest whole number coefficient.

___KOH + ___CO2 ---> ___K2CO3 + ___H2O

a) 2:1:1:4
b) 1:1:1:1
c) 2:1:1:2
d) 2:1:1:1
e) 2:2:1:4

12. Balance the following chemical equation with the smallest whole number coefficients. What is the value of the coefficient of the CO2 species?

___C4H10 + ___O2 ---> ___CO2 + ___H2O

a) 5
b) 4
c) 13
d) 10
e) 8

KEY

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