Quantative Chemistry

What is the law of conservation of mass?

No atoms are lost or made during a chemical reaction

In a chemical reaction, is there any change in the overall mass of the substances?

No

Give 2 reasons why the total mass may appear to change during a chemical reaction

the gas may react with other chemicals increasing the mass

the gases may escape decreasing the mass

What is the rule for balancing equations?

Total number of reactants = Total number of products

What is the definition of relative atomic mass?

The average mass of all the isotopes of that element

What is the symbol for relative atomic mass?

Ar

On a periodic table, is the RAM the larger or smaller number for each element?

The larger number

What is the symbol for relative formula mass?

Mr

What is the molar volume of a gas?

24 dm ³ (24,000 cm³)

What is the concentration of a solution?

The amount of solute dissolved in a volume of solution

How do you convert cm³ → dm³

Divide by 1000

How do you convert dm³ → cm³

Multiply by 1000

What are the 3 forms of formula that links mass, Mr and moles?

• mass = moles x Mr

• moles = mass/Mr

• Mr = mass/moles

What is molar ratio?

the ratio between the moles in a balanced equation

What is the molar ratio in : 1N₂ + 3H₂ → 2NH₃

1 : 3 : 2

What is the molar ratio in : 1Zn + 2HCl → 1ZnCl₂ + 1H₂

1:2:1:1

What is the formula that links moles, mass and Mr?

mass = moles x Mr

What is a mole?

A unit of measure (6.02 × 10²³)

What is Avogadro’s constant?

The value of the constant is 6.02 × 10²³

Rearrange the formula to get moles by itself: mass = moles x Mr

moles = mass/Mr