Moles and titration

Question 1

There are ….. atoms in …g of Carbon

Answer 1

6.023x10 to the power of 23, atoms in 12g of carbon

Question 2

What is the concentration of a solution measured in?

Answer 2

moles per dm cubed (moles per liter)

So one mole of stuff in one 1dm3 of solution has a concentration of 1 mole per dm3

Question 3

The more … you dissolve in a given …. the more crowded the solute …. are and the more … the solution becomes.

Answer 3

solute, volume, molecules, concentrated

Question 4

What can concentration also be measured in? (weight)

Answer 4

Grams per dm3

Question 5

What are titrations used to find out?

Answer 5

How much exactly of acid is needed to neutralise a quantity of alkali, or the other way around.

Question 6

How is the titration experiment done to find how much of x is needed to neutralise y?

1. put what and what in what
2. add….
3. the what does what
4. Record…

Answer 6

Put the alkali in the flask along with indicator methyl orange, not universal indicator as it changes colour gradually, and you need a definite colour change.
Add the acid a drop at a time from a burette continuously swirling the flask to mix.
The indicator changes colour when all the alkali has been neutralized - it goes yellow in alkalis and red in acids
Record the amount of acid needed to neutralise the alkali, then repeat, take a mean of the results

Question 7

What is the formula for concentration moles and volume?

Answer 7

Concentration = moles / volume

Question 8

If they ask for the concentration of x in moles per dm3:

1. what you know
2. balance and work out
3. now find out …

Answer 8

1. Work out how many moles of the known substance you have using the formula
2. Write down the balanced equation of the reaction, work out how many moles of the unknown concentration substance you have by looking at their ratios
3. Work out the concentration of the unknown substance in mol/dm3

Question 9

If they ask for the concentration of x in grams per dm3:

1. formula
2. work out … using formula
3. now convert …

Answer 9

1. moles = mass / Mr
2. work out the relative formula mass, Mr
3. Convert the concentration of in moles into grams : mass = moles x Mr