Balancing Equations And Moles

Question 1

What’s the empirical formula?

Answer 1

Shows ratio between elements on chemical compounds.

Calculated form masses of each of the elements compounds.

Ratios only work by whole numbers.

Question 2

How to do empirical formula.

Answer 2

• Divide % by compound’s element’s atomic masses to get ratio. (Mass %/molar mass = molar ratio).
• Divide answer for each element by smallest ratio calculated
• If not a whole number, multiply answer by a whole number so they all become whole intigers.
• Write out molecules symbols.

Question 3

How do you work out molecular formula?

Answer 3

Molecular formula = relative molecular mass/empirical mass.

Multiply each part to get a whole number.

Question 4

How do you balance equations?

Answer 4

1. Write as word equation
2. Write out all formulas
3. Write out number of each element on both sides.
4. Make number of each atom equal to each side. But you can only change formula of compound not elements.
5. Check there’s same number of atoms on each element on both sides.

Question 5

True or false? In reactions you always finish with the same amount you started with.

Answer 5

True.

Question 6

Why do we never use 1 molecule of a substance?

Answer 6

It’s too small.

Question 7

What do moles equal?

Answer 7

1 mol. = Atomic mass of the substance

Question 8

How many atoms in 1 mol of substances?

Answer 8

6.023x10^(23)

Question 9

True or false? A substances mole equals it’s atomic mass.

Answer 9

True.

Question 10

Good example of a mole.

Answer 10

6.023x10^(23) atoms of carbon in 12 grams of carbon so 12g = 1 mol of carbon.

Question 11

What is relative formula mass? Details?

Answer 11

Addition of atomic masses of all compounds elements.

Can round atomic masses to 1sf when working out

If more than one element then multiply elements atomic mass by its quantity.

Question 12

What are the equations for both titration triangles?

Answer 12

Triangle 1
Mass = moles x relative formula mass
Moles = Mass/relative formula mass
Relative formula mass = mass/ moles

Triangle 2
Moles = concentration x litres
Litres = moles/ concentration
Concentration = moles/ Litres

Question 13

What do you always have to remember when working with titrations triangle 2?

Answer 13

Always divide unit by 1000 to get litres if it’s not in litres already.