Section 1
Section 2
Section 3
Section 4
More Practice Problems
100
What is the SI base unit used to measure the amount of a substance?
The Mole
100
What is the mass in grams of mole of any pure substance?
Molar Mass
100
What is the mass of 5.0 x 1021 molecules of water?
0.15 g
100
What relationship is described by the formula below? (mass of the element/mass of the compound) x 100
Percent Composition
100
Determine the number of atoms in 3.54 mol S.
2.13 x 10^24
200
What does the number 6.022 x 10^23 represent?
Avogadro's Number
200
The Molar Mass of any element is numerically equivalent to its atomic mass and has the unit ___?
g/mol
200
What is the mass of 1.0 x 1012 molecules of O2?
5.3 x 10-11 g
200
How can the actual molecular formula be determined?
From the molar mass divided by the mass of the empirical formula
200
How many moles of chlorine are in 100g chlorine (Cl)?
2.82
300
1 mole= (?) Liters 1 mole= (?) Molecules 1 mole= (?) of the element
22.4 Liters 6.022 x 10^23 Molecules Molar Mass of the Element
300
Easy Practice: 1 mole of C atoms= (?) 1 mole Mg atoms = (?) 1 mole of Cu atoms = (?)
1 mole of C atoms= 12.0 grams 1 mole Mg atoms = 24.3 grams 1 mole of Cu atoms = 63.5 grams
300
How many moles of hydrogen atoms are present in 2.0 moles of ammonia NH3?
6.0 mol
300
Analysis of a covalent compound showed that it contained 14.4% hydrogen and 85.6% carbon by mass. What is the empirical formula for this compound?
CH2
300
What is the mass of 1.000 mole of carbon atoms?
12.01 grams
400
At what temperature and pressure does 1 mole = 22.4 Liters? (in Kelvin and ATM)
STP or 273 degrees Kelvin and 1 ATM
400
Convert Moles to Mass 1.25 moles of Nitrogen=____ grams
35.0 grams (since Nitrogen is diatomic multiply AMU by 2)
400
What is the molar mass of H2CrO4?
118 g
400
A sample of liquid contains 0.059% hydrogen and 0.94% oxygen. What is the empirical formula?
HO
400
Which of the following quantities would have the greatest mass: one mole of carbon atoms, one mole of helium atoms, one mole of neon atoms?
one mole of neon atoms
500
Convert 100 grams of C6H12O6 to molecules
3.341 x 10^23 molecules
500
35.4 g of Cu to Atoms
3.35 x 10^13 atoms
500
Acetic acid has the molecular formula CH3COOH. How many atoms of oxygen in 60 grams of acetic acid?
1.2 x 1024 atoms of oxygen
500
The empirical formula for a sample of liquid is HO. The molecular weight is 34.0 grams/mole. What is the molecular formula?
H2O2
500
What is the mass of 5.0 x 1021 molecules of water?
0.15 g
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