click below
click below
Normal Size Small Size show me how
Chemistry - Chap 7
Section 3 - Using Chemical Formulas
Question | Answer |
---|---|
Hydrogen atoms have an average atomic mass of | 1.007 94 |
Oxygen atoms have an average atomic mass of | 159994 amu |
The percentage by mass of each element in a compound | Percentage composition |
The sum of the average atomic masses of all atoms represented in the formula of any molecule, formula unit, or ion. | Formula mass |
A compounds molar mass and formula mass are | numerically equal |
What is the formula mass for KCIO3 | 122.55 amu |
The molar mass of a compound is calculated by | Summing the masses of teh elements present in a mole of the molecules or forumla units that make up the compound. |
What is the molar mass of barium nitrate, Ba(NO3)2? | 261.35 g/mol |
The molar mass of a compund can be used as a conversion factor to relate | An amount in moles to a mass in grams for a given substance. |
To convert a known amount of a compound in moles to a mass in grams, you should | multiply the amount in moles by the molar mass. amount in moles x molar mass (g/mol) = mass in grams. |
What is the mass in grams of 2.50 mol of oxyge gas | 75 g (2.50 mol x 30 g/mol) |
How To convert a known mass of a compound in grams to an amount in moles, | The mass must be divided by the molar mass OR invert the molar mass and multiply so that the units are easily canceled. |
To find teh mass percentage of an element in a compound | Divide the mass of the element in a sample of the compound by the total mass of teh sample, then multiply this by value by 100 |
The percentage by mass of each element in a compound | Percentage composition |
The mass percentage of an element in a compound is the same regardless of | the sample's size. |
How many moles of atoms of each element are there in one mole of the following compound: Al2S3 | 2 mol Al, 3 mol S |
How many moles of atoms of each element are there in one mole of the following compound: NaNO3 | 1 mol Na, 1 mol N, 3 mol O |
How many moles of atoms of each element are there in one mole of the following compound: Ba(OH)2 | 1 mol Ba, 2 mol O, 2 mol H |
What is the molar mass of each of the compounds: Al2S3 | 150.17 g/mol |
What is the molar mass of each of the compounds: NaNO3 | 85.00 g/mol |
What is the molar mass of each of the compounds: Ba(OH)2 | 171.35 g/mol |
What is the mass in grams of 2.50 mol of oxygen gas? | 75g (2.50 mol x 30 g/mol) |
Find the percentage composition of PbCl2 | 74.51% Pb, 25.49% Cl |
Find the percentage composition of Ba(NO3)2 | 52.55% Ba, 10.72% N, 36.73% O |
Find the mass percentage of water in ZnSO4 * 7H2O. | 43.85% H2O |