PLEASE HELP

[pawesome2]

Can you help me with this question? My teacher wouldn't help me because she said we didn't need to do this question, but I want to know what the answer is anyway.

I really appreciate help, thank you.

 

QUESITON = student 4 only added 5cm3 of the NaOH instead of 10cm3. Show by calculation that student 4 did not have an excess of sodium hydroxide

 

 

Hydrolsis ester - PROCEDURE

 

1.Add 2cm3 of methylbenzoate flask, record mass

Add 10cm3 dilute 2.0moldm-3 NaOH solution (in excess), about 10cm3 of ethanol and anti bump granules. fit the water condesner on

 

2. heat flask gently without allowing contents to boil for about 5 min. and then boil gently under reflex for futher 15 min

 

3. allow contents flask to cool remove condenser and decant solution from antibump graniles into a beaker. add 10 drops methyl orange indicator and acidify with 2.0 moldm-3 HCl. filter product under reduced pressure

 

4. recrstyallise product - dissolve solid in minim amount of boiling water to allow to cool slowly, when cool filter purified product under reduced pressure and allow dry in air on filter paper

 

5. dry sample of product by pressing between filter papers and determine mpt (which is greater than 100 degrees) record value

 

6. weigh dry product and record mass

[Chap]

find the number of moles of methlybenzoate(let's call the result A). Then find the number of moles in 5cm3 of NaOH(let's call the result B). Write out the balanced reaction equation between NaOH and methlybenzoate. Use the ratio between the methylbenzoate and NaOH to calculate the number of moles of NaOH required to react completely with the methlybenzoate (result A). Check whether this result is greater than B. If so, NaOH is NOT in excess.