Vocab
the mass in amus of an atom of an element
atomic mass
How many molecules are in 4.50 moles of H2O?
2.71 × 1024 molecules
How many molecules are in 4.50 moles of H2O?
2.71 × 1024 molecules
A compound has the empirical formula C2H3O and a molar mass of 172 g. What is its molecular formula?
C8H12O4
Determine the number of moles in 625 L of H2 gas at STP.
27.9 mol
the number of representative particles in a mole of a substance
Avogadro’s number
or
6.02 × 1023
The chemical formula of aspirin is C9H8O4. What is the mass of 0.200 mol of aspirin?
36.0 g
How many atoms are contained in 12.5 grams of silver?
6.97 × 1022 atoms
The empirical formula of a compound is CH2F. The molar mass of this compound is 66.0 g. The molecular formula of the compound is:
C2H4F2
What is the percentage of aluminum in Al2(SO4)3?
15.8%
0°C and 101.3 kPa
standard temperature and pressure
What is the molar mass of MgCl2?
95.3 g
The molar mass of one oxygen is:
16.0 g.
What is the mass of hydrogen in 50.0 g of propane, C3H8?
9.1 g
The polymer used for the nonstick surface of cooking utensils is 24.0% C and 76.0% F by mass. What is the empirical formula of this polymer?
CF2
the percent by mass of each element in a compound
percent composition
What is the volume (in liters at STP) of 2.50 mol of carbon monoxide?
56.0 L
What is the molar mass of C3H8?
44.0 g
What is the volume, in liters, of 3.75 moles of O2 gas at STP?
84.0 L
Calculate the percent composition of Mg(NO3)2 to 3 sig figs.
Mg= 16.4%
N=18.9%
O=64.7%
the formula that gives the lowest whole-number ratio of the elements in a compound
empirical formula
How many moles of SO3 are in 2.4 × 1024 molecules of SO3?
4.0 mol
What is the percent by mass of carbon in acetone, C3H6O?
62%
How many grams are in 6.50 moles of H2SO4?
638 g
What is the volume, in liters, of 15.0 kg of CO2 at STP?
7.63 x 103 L CO2