Question

A lab team places 0.250g of an unknown solid acid in an Erlenmeyer flask. They neutralize the solid acid with 15.0ml of 0.210 M Na(OH)(aq). One mole of the acid reacts with one mole of the base. Calculate the molar mass of the unknown solid acid O 158 g/mol 0 7.9 g/mol 79.4 g/mol 0 763 g/mol​

Answer 1

Molar mass of the unknown acid is 79 grams

Step-by-step explanation:

We have to first get moles in 15.0 ml of sodium hydroxide solution:

`{ \sf{1 \: l \: of \:NaOH \: contains \: 0.210 \: moles }} \\ { \sf{0.015 \: l \: of \: NaOH \: contain \: (0.015 * 0.210) \: moles }} \\ { \underline{ = 0.00315 \: moles \: of \: NaOH}}`

since mole ratio of acid : base is 1 : 1, so;

moles of acid that reacted is 0.00315 moles of the unknown acid.

then we've to get molar mass:

`{ \sf{0.00315 \: moles \: of \: acid \: weigh \: 0.250 \: g}} \\ { \sf{1 \: mole \: of \: acid \: weighs \: ( (1 * 0.250)/(0.00315) ) \: g}} \\ { \underline{ = 79.4 \: g \approx79 \: grams}}`