C3-Quantitative Chemistry

Question 1

What is the relative atomic mass abbreviated to?

Answer 1

Aᵣ

Question 2

What is the formula mass abbreviated to?

Answer 2

Mᵣ

Question 3

What is the sum to create relative formula mass?

Answer 3

All of the relative atomic masses added together:
For example for H₂SO₄ would be (1x2) + 32+ (16x4)

Question 4

What is the mole?

Answer 4

The relative atomic mass in grams

Question 5

What is the mole abbreviated to?

Answer 5

Mol

Question 6

What is the number of atoms in a mole called?

Answer 6

The Avogadro Constant

Question 7

What is the Avogadro Constant?

Answer 7

6.02 x 10²³

Question 8

How do you get the number of moles from masses?

Answer 8

You divide the mass in grams by the Aᵣ or Mᵣ
number of moles=mass (g) / Aᵣ or Mᵣ

Question 9

How do you get the masses from number of moles?

Answer 9

You multiply the number of moles by the Aᵣ or Mᵣ
mass (g) = number of moles x Aᵣ or Mᵣ

Question 10

For mole calculations what do you write in the table going down?

Answer 10

• mass (g)
• Mᵣ
• moles
• Equation ratio

Question 11

What is the number of molecules in a chemical formula?

Answer 11

Large number before all of the letters and smaller numbers

Question 12

What is the limiting reactant?

Answer 12

The reactant that gets used up first-the reactant not in excess

Question 13

What is the amount of product determined by-the limiting or excess reactant?

Answer 13

The limiting reactant

Question 14

What is the formula for percentage yield?

Answer 14

actual mass of product produced/theoretical mass of product produced

Question 15

What factors affect percentage yield?

Answer 15

• Raw materials may not be pure
• Some of the products may be left behind
• The reaction may not be finished
• Some reactants may have unexpexted by-products

Question 16

How do you calculate atom economy?

Answer 16

% atom economy = Mᵣ of desired product/Mᵣ of all products

Question 17

How do you calculate the concentration of a solution?

Answer 17

concentration (g/dm³) = amount of solute (g)/volume of solution (dm³)

Question 17

How do you convert from cm³ to dm³?

Answer 17

You divide by 1000

Question 18

What is titration used to measure?

Answer 18

It is used to measure accurately what volumes of acid and alkali react together completely

Question 19

What is the point in which an acid and alkali are completely reacted?

Answer 19

The end point

Question 20

What do you use to show the end point of the reaction between an acid and alkili?

Answer 20

An indicator

Question 21

What is the 7 step process of carrying out a titration?

Answer 21

1) Measure out a known volume of alkali into a conical flask using a volumetric pipette and pipette filler
2) Put a burette into a special burette clamp
3) Pour the acid into the burette using a funnel up to the 0cm³ line
4) Add 2 or 3 drops of a suitable indicator to the conical flask and swirl to mix
5) Open the burette tap slowly and swirl the mixture until you notice a change in colour
6) When you see the first signs of colour change slow the acid down and keep on adding drops until the colour change is clear and permanent
7) Repeat the experiment to spot anomalous results and record the final burette volume-the difference between the start and end volume is called the titre

Question 22

What is the volume of 1 mole of any gas at room temperature (20)° and pressure (1 atmosphere)?

Answer 22

24dm³ or 24000cm³

Question 23

What is the formula for the number of moles in a gas?

Answer 23

number of moles in a gas = volume of gas (dm³) / 24dm³