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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 1024

200

What does the number 6.022 x 1023 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 1023 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 1023 molecules

500

35.4 g of Cu to Atoms

3.35 x 1013 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