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Chemistry AS question URGENT help needed watch

1. 2.5 g of a sample of impure ethanedioic acid, H2C2O4.2H2O, was dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 21.3 cm3 were required to neutralise 25 cm3 of 0.1 moldm-3 NaOH. Given that ethanedioic acid reacts with NaOH in a 1:2 ratio, calculate the percentage purity of the sample.
2. (Original post by imaan567)
2.5 g of a sample of impure ethanedioic acid, H2C2O4.2H2O, was dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 21.3 cm3 were required to neutralise 25 cm3 of 0.1 moldm-3 NaOH. Given that ethanedioic acid reacts with NaOH in a 1:2 ratio, calculate the percentage purity of the sample.
Firstly, work out the number of mole of NaOH that used to neutralize the acid - mole of NaOH = 0.1 x 25/1000
Secondly, work out the moles of acid in 21.3 cm3, mole of acid in 21.3 cm3 = mole of NaOH/2
Thirdly, work out the moles of acid in 250cm3 by timing the moles of acid in 21.3 cm3 by 250/21.3
Fourthly, multiply the mole of acid in 250cm3 by the Mr of the acid to get the mass of acid.
Lastly, devide the mass by 2.5g and times 100 to get % purity.
Hope this help😀
3. (Original post by Earth1)
Firstly, work out the number of mole of NaOH that used to neutralize the acid - mole of NaOH = 0.1 x 25/1000
Secondly, work out the moles of acid in 21.3 cm3, mole of acid in 21.3 cm3 = mole of NaOH/2
Thirdly, work out the moles of acid in 250cm3 by timing the moles of acid in 21.3 cm3 by 250/21.3
Fourthly, multiply the mole of acid in 250cm3 by the Mr of the acid to get the mass of acid.
Lastly, devide the mass by 2.5g and times 100 to get % purity.
Hope this help😀
Thanks a million! I understand it now finally, spent ages on it haha
4. 4. 2.5 g of a sample of impure ethanedioic acid, H2C2O4.2H2O, was dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 21.3 cm3 were required to neutralise 25 cm3 of 0.1 moldm-3 NaOH. Given that ethanedioic acid reacts with NaOH in a 1:2 ratio, calculate the percentage purity of the sample.

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