Moles Test Review

The Mole

100

What is the numerical value for a mole?

6.02 x 10^23

200

What element was the mole derived from -which is the basis for chemistry in general?

carbon-12 (the number of atoms in 12g of carbon-12)

300

Which scientist is responsible for our use of the mole?

Avagadro

400

Name 3 "representative particles" the mole can be used to count.

atoms, molecules, formula units, ions, particles

500

Why do we use the mole in chemistry?

it is used as a counting unit because individual atoms or molecules are far too small to work with by themselves

Conversions

100

What is the molar mass of water?

18.0g

200

How many moles are there in 76.44 g H₃PO₄?

0.78 mol

300

How many liters are in 6.2 mol Cl₂?

138.88 liters

400

How many representative particles are in 35.4 mol CO₂?

2.13x10^25 molecules

500

Why can't you convert directly from particles to grams(and vice versa) - what must the conversion be converted to first?

You have to convert to moles first

Empirical Formulas

100

What is an empirical formula?

the atoms of a molecular formula shown in the smallest ratio

200

What is the empirical formula for carbon monoxide?

CO

300

What is the empirical formula for glucose? (C₆H₁₂O₆)

CH₂O

400

What are the steps to finding the empirical formula?

percent to mass

mass to mole

divide by smallest mole

multiply if not whole numbers 

500

What is the empirical formula for a compound containing 50.0% C, 5.5% H, and 44.4% O?

C₃H₄O₂

Molecular Formulas

100

What is a molecular formula?

the chemical formula with atoms in the ratios they actually occur

200

What is the molecular formula for copper II sulfate?

CuSO₄

300

What are the steps you must follow to find the molecular formula?

find the empirical formula and calculate the empirical formula mass

divide the molar mass by the empirical formula mass

multiply the empirical formula by this number

400

Find the molecular formula for a compound whose molar mass is 124.06 and empirical formula is CH₂O₃.

C₂H₄O₆

500

What is the molecular formula with 960 grams of a compound containing 65.0% Cr and 35.0%O?

Cr₁₂O₂₁

Hydrates

100

What is a hydrate?

a salt with water bonded to the ions in the crystal structure

200

What is the name for BaCl₂•7H2O

barium chloride heptahydrate

300

What is the name for FeSO₄•6H2O?

iron II sulfate hexahydrate

400

The term for a substance that has had the water removed

anhydrous

500

A 15.67 g sample of a hydrate of magnesium carbonate was heated to drive off the water. The mass was reduced to 7.58 g. What is the formula of the hydrate?

MgCO3 · 5H2O