Chemical Quantities Review
Chemistry CP
1.
Name the representative particle for the following substances:
 N ___________________________  CO
2 _________________________________________
 N + ___________________________
 N

2
___________________________
NaHCO
3
________________________
 C
6
H
6 _________________________________________
 Na
2
SO
4
_________________________
 NaOH _________________________
2.
Calculate the molar mass of the following substances:
 C
6
H
6
 Ca(NO
3
)
2
__________________________________
__________________________________
 MgSO
4
 7H
2
O __________________________________
3.
How many moles are in 20.1 g of HC
2
H
3
O
2
?
4.
Calculate the mass of 15.6 moles of CuSO
4
 5H
2
O.
5.
How many molecules are in 100.5 g N
2
O?
6.
Calculate the volume of 67.8 g of Cl
2
gas at STP.
7.
How many oxygen atoms are in 523 molecules of HC
7
H
5
O
2
?
8.
Calculate the mass of 2.35 x 10 15 molecules of CH
4
.
9.
Calculate the percentage composition of Ca(OH)
2
.
10.
How many grams of zinc could be extracted from 1.00 kg of Zn(NO
3
)
2
?

11.
A compound with a molar mass of 86.17 g/mol that contains 83.62% carbon and 16.38% hydrogen.
Determine the empirical and molecular formula.
12.
A 3.0 g sample of Na2CO3•H2O is heated to constant mass. How much anhydrous salt remains?
 Know the four representative particles and be able to determine what the R.P. is for a given substance.
 Know how to find the molar mass / molecular weight (MW) of a given substance.
 Know how to determine the number of atoms / ions present in one molecule or formula unit of a given substance.
 Know how to convert between units of mass, moles, volume, representative particles, and atoms or ions when appropriate.
 Know how to calculate percent composition.
 Know how to calculate the mass of some part of a compound that could be recovered. o For example, a typical bottle of fingernail polish contains 215.25 mg of tin (IV) oxide.
What mass of tin is present in this amount?
 Begin calculations with the given value.
 PAY ATTENTION TO UNITS.
 Convert to the mole before converting to any other unit
 Round to the hundreth’s place when calculating molar mass.
 Attach the appropriate units to all values.
 Give your answer with the same number of significant digits as the given value when converting between units.
 Use Avogadro’s number (6.02 x 10 representative particles.
23 representative particles / mole) to convert to and from
 Use molar mass to convert to and from mass.
 Use molar volume (22.4 L / mole) to convert to and from volume of a gas at STP.
 Remember that density = mass (g) / volume (L)
Remember: 1 mole = 6.02 x 10 23 R.P.’s
1 mole = MW in grams
1 mole = 22.4 L of gas @STP