Show:
Measuring Matter
Mass and The Mole
Moles of Compounds
Empirical and Molecular Formulas
Formulas of Hydrates
100

What is the numerical value of Avogadro's number?

6.02x10^23

100

What is the mass in grams of one mole of any pure substance?

Molar Mass

100

CuSO4.5H2O

Copper Sulfate Pentahydrate

100

What is the percent by mass of each element in a compound?

Percent Composition

100

What is a compound that has a specific number of water molecules bound to its atoms?

A Hydrate

200

What is the SI base unit used to measure the amount of a substance?

The mole

200

Why do one mole quantities of two different substances have different masses?

The substances have different compositions.

200

What is the C-Cl-F raito in CCl2F2?

1:2:2

200

What is the formula with the smallest whole-number mole ratio of the elements?

Empirical Formula

200

What happens when a hydrate is heated?

Water molecules are driven off leaving an anhydrous compound, or one "without water".

300

How many atoms of potassium does 1 mol of potassium contain?

6.02x10^23 potassium atoms

300

Explain how you would convert from number of atoms of a specific element to its mass.

Convert the number of atoms to moles, then multiply moles by the molar mass of the element.

300

5.50g compound x 1 mol compound/185.0g compound

0.0297 mol compound

300

What specifies the actual number of atoms of each element in one molecule or formula unit of the substance?

Molecular Formula

300

How can you determine the formula of a hydrate? 

You must find the number of moles of water associated with 1 mol of the hydrate.

400

2.11x10^24 molecules sucrose x 1 mol/6.02x10^23 molecules sucrose

3.50 mol sucrose

400

Calculate the mass of 5.22 mol of He

20.9 g He

400

What information is provided by the formula for ptassium chromate (K2CrO4)?

One mole of K2CrO4 contains two moles of K^+ ions and one mole of CrO4^-2 ions.

400

Express the composition of sucrose (C12H22O11) as the mass percent of its elements.

144 g C

22 g H

176 g O

400

What three hydrates does Calcium Chloride form?

Monohydrate, dihydrate, hexahydrate
500

The recommended daily allowance of selenium in your diet is 8.87x10^-4 mol. How many atoms of selenium is this?

5.34x10^20 atoms Se

500

Convert to mass in grams.

4.22x10^15 atoms U

0.000001984 g U
500

How many moles of oxygen atoms are contained in 2.50 mol of KMnO4?

10 mol O

500
What is the empirical formula of a compound that contains 10.52 g Ni, 4.38 g C, 5.10 f N?

1 mol Ni

1.936 mol C

2.031 mol N

500

What are some hydrates used for?

To store solar energy.