1
The percent by mass of each element in a compound.
percent composition
The number of representative particles of a substance present in 1 mole of that substance.
Avogardro's number
An atom, an ion, or a molecule, depending upon the way a substance commonly exists.
representative particle
The SI unit used to measure amount of substance.
mole
The smallest whole number ratio of the atoms in a compound.
empirical formula
How many hydrogen atoms are in 10 molecules of water?
20 atoms
The mass of a mole of NaCl is the ____________.
molar mass
To determine the formula of a new substance, one of the first steps is to find the _____________.
What is the molar mass of chlorine gas?
71 g
density
What information is needed to calculate the percent composition of a compound?
formula & atomic mass of elements
What are the conditions of temperature and pressure for STP?
For which of the following conversions does the value of the conversion factor depend upon the formula of the substance?
a. mass of any substance to moles
b. volume of gas to moles
c. density of gas to molar mass
d. moles of any substance to number of particles
a. mass of any substance to moles
Which of the following is NOT true about empirical and molecular formulas?
a. The molecular formula of a compound can be some whole-number multiple of its empirical formula.
b. Several compounds can have the same empirical formula, but have different molecular formulas.
c. The molecular formula of a compound can be the same as its empirical formula.
d. The empirical formula of a compound can be triple its molecular formula.
d. The empirical formula of a compound can be triple its molecular formula.
What is the molar mass of AuCl3?
303.5 g/mol
Given 1 mole of each of the following gases at STP, which gas would have the greatest volume?
He
O2
SO3
They all would be the same
Find the molar mass of PCl3.
137.5 g/mol
All of the following are equal to Avogadro's number EXCEPT...
a. the number of atoms of gold in 1 mol Au
b. the number of molecule of nitrogen in 1 mol N2
c. the number of atoms of bromine in 1 mol Br2
d. the number of molecules of carbon monoxide in 1 mol CO
c. the number of atoms of bromine in 1 mol Br2
Find the number of moles of argon in 640 g of argon.
16 moles of argon
What is the volume, in liters, of 1.2 mol of CH4 gas at STP?
26.9 liters
Which of the following gas samples would have the largest number of representative particles at STP?
a. 10 L He
b. 7 L O2
c. 0.007 L H2
a. 10 L He
Calculate the percent composition of oxygen in H2O2.
94%
What is the percent composition of hydrogen in C7H16?
16 %
Which of the following compounds have the same empirical formula?
a. C7H14 and C10H20
b. C4H10 and C10H4
c. CO2 and SO2
a. C7H14 and C10H20
How many moles of CO are in 170 grams of CO?
6.1 moles
How many molecules are in 3.4 mol CO?
2.05 x 1024 molecules
Calculate the mass, in grams. of 3.5 mol of Fe(OH)2.
315 grams
How many moles are in 43 g H2O?
2.4 moles
Calculate the mass of carbon in 23 grams of CO.
9.9 g C
How many moles of tungsten atoms are in 3.5 x 1025 atoms of tungsten?
58.1 moles