Chemistry Past Paper Question Watch

luisahorton
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calculations aren't my strongest point, i have no idea what to do or where to start so if anyone could answer these i'd be so grateful

thank

4. A student carries out a titration to find the concentration of some sulfuric acid. The student finds that 25.00 cm^3 (cubed) of 0.0880 mol.dm^3 aqueous sodium hydroxide, NaOH, is neutralised by 17.60 cm^3 of dilute sulfuric acid, H2SO4.


H2SO4 + 2NaOH = Na2SO4 + 2H2O

(i) Calculate the amount, in moles, of NaOH used.
(ii) Determine the amount, in moles, of H2SO4 used.
(iii) Calculate the concentration, in mol.dm^3, of the sulfuric acid.

(c) After carrying out the titration above, the student left the resulting solution to crystallise. White crystals formed, with a formula of Na2SO4●xH2O and a molar mass of 322.1 g.mol-1
(i) What term is given to the '●xH2O' part of the formula?
(ii) Using the molar mass of the crystals, calculate the value of x.
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charco
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(Original post by luisahorton)
calculations aren't my strongest point, i have no idea what to do or where to start so if anyone could answer these i'd be so grateful

thank

4. A student carries out a titration to find the concentration of some sulfuric acid. The student finds that 25.00 cm^3 (cubed) of 0.0880 mol.dm^3 aqueous sodium hydroxide, NaOH, is neutralised by 17.60 cm^3 of dilute sulfuric acid, H2SO4.


H2SO4 + 2NaOH = Na2SO4 + 2H2O

(i) Calculate the amount, in moles, of NaOH used.
(ii) Determine the amount, in moles, of H2SO4 used.
(iii) Calculate the concentration, in mol.dm^3, of the sulfuric acid.

(c) After carrying out the titration above, the student left the resulting solution to crystallise. White crystals formed, with a formula of Na2SO4●xH2O and a molar mass of 322.1 g.mol-1
(i) What term is given to the '●xH2O' part of the formula?
(ii) Using the molar mass of the crystals, calculate the value of x.
This is just a copy-paste of your homework.

You must have some idea where to start. It is not fair to expect people just to post the answers. If they do it won´t help you tackle similar problems in the future.
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dazzer19
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Well, to start with, to work out moles you need to do mass over molar mass. Yet there is no mass on the description? Or am I just missing it?
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BlossomS
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I would give you the answers but that won't help you much at all.

N = V x C
n = m/M

To begin with, try and see if you can see a link between the question and those equations

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charco
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(Original post by dazzer19)
Well, to start with, to work out moles you need to do mass over molar mass. Yet there is no mass on the description? Or am I just missing it?
moles of solute is found from molarity (concentration) x volume (litres)
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