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Chemistry help

"Calculate the concentration of a 25cm^3 sodium hydroxide solution when it is titrated with 44.75cm^3 of 0.5mol dm^-3 hydrochloric acid"

Not sure how to do this any help would be much appreciated

Calculate moles of HCL by converting its volume from cm to dm (divide by 1000) then as it’s a 1:1 molar ratio divide the calculate moles by the volume of NaOH and this will give you the concentration.

Reply 3

Ðeggs

I got 8.95 x 10^-7 as the concentration of NaOH.

Reply 4

Travv

I’ll break it down as easily I can, I struggled with titration calculations but they’re actually quite easily.

You need to use and rearrange the formula
n = vc where n is the number of moles, v is volume and c is concentration.

The first thing to do is convert cm3 to dm3 by dividing the values by 1000, giving us 0.025 dm3 NaOH and 0.04475 dm3 HCl.

You have the concentration of HCl, so we calculate the number of moles with n = vc
n = 0.04475 x 0.5 = 0.022375 moles HCl

There is a 1:1 mole ratio, so we have 0.022375 moles NaOH aswell.

Now we know moles and volume for NaOH, divide the moles by the volume to get 0.895 mol/dm3

I hope that explains it, I did working out on paper I can send a picture of if you’d like.

(edited 4 years ago)

Reply 5

JJJJJAAAAMES

Original post by Travv

I’ll break it down as easily I can, I struggled with titration calculations but they’re actually quite easily.

You need to use and rearrange the formula
n = vc where n is the number of moles, v is volume and c is concentration.

The first thing to do is convert cm3 to dm3 by dividing the values by 1000, giving us 0.025 dm3 NaOH and 0.04475 dm3 HCl.

You have the concentration of HCl, so we calculate the number of moles with n = vc
n = 0.04475 x 0.5 = 0.22375 moles HCl

There is a 1:1 mole ratio, so we have 0.22375 moles NaOH aswell.

Now we know moles and volume for NaOH, divide the moles by the volume to get 8.95 mol/dm3 (I thought that was a bit high, but I checked and it’s all good)

I hope that explains it, I did working out on paper I can send a picture of if you’d like.

your moles of hcl is wrong, it should be 0.022375 mol

the final answer is 0.895 mol dm^-3

Reply 6

Travv

Original post by Deggs_14

I got 8.95 x 10^-7 as the concentration of NaOH.

Not sure what you did, but to check my answer I always calculate the moles from the values I got. 8.95 x 0.025 is 0.22375 (the correct number of moles)

Correct me if I did something wrong but I think that’s right?