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A Level Chemistry Year 1 > Formulas and Equations > Flashcards

Flashcards in Formulas and Equations Deck (21)
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1

What is the empirical formula?

The smallest whole number ration between atoms of each element in a compound

2

What is the molecular formula?

The actual number of atoms of each type of element in a molecule

3

What are the 3 steps, if you know the empirical formula and the molecular mass of a compound, to calculate it's molecular formula?

1- Find the empirical mass (mass of the empirical formula)
2-Divide the molecular mass by the empirical mass
3-Multiply the empirical formula by that number

4

What are the 4 steps for calculating the empirical formula from experimental data?

1-Use the equation, moles = mass / Mr, to work out how many moles of each product you have
2-Use the moles of each product to work out how many moles of each atom you started with
3-Write down the ratio of moles present at the start and then divide by the smallest to get the simplest whole number ratio
4-This is the empirical formula

5

What are the 3 steps for calculating the empirical formula from percentage compositions?

1-Assume you've got 100g of the compound, so you can turn the percentages into masses, then work out the moles of each element
2-Divide each number of moles by the smallest number of moles you found to get the smallest whole number ratio
3-Apply the numbers from the ratio to the formula

6

What 2 things do you need to know to be able to calculate the molecular formula?

Empirical formula and the molar mass

7

How do you find the factor that you need to multiply the empirical formula by to get the molecular formula?

Divide the molar mass by the empirical formula

8

What are the 4 state symbols?

s = solid
l = liquid
g = gas
aq = aqueous (solution in water)

9

How are ions formed?

Formed when electrons are transferred from one atom to another

10

What charge of ion does Zinc form?

2+

11

What charge of ion does Silver form?

1+

12

What charge of ion does Iron (II) form?

2+

13

What charge of ion does Iron (III) form?

3+

14

What charge of ion does Copper (I) form?

1+

15

What charge of ion does Copper (II) form?

2+

16

What is the formula of a Nitrate ion?

NO3 -

17

What is the formula of a Carbonate ion?

CO3 2-

18

What is the formula of a Sulfate ion?

SO4 2-

19

What is the formula of a Hydroxide ion?

OH -

20

What is the formula of a Ammonium ion?

NH4 +

21

How are ionic compounds made?

When positive and negative ions bond together