urgent help people thanks so much

Grignard reagent is a compound in which magnesium is bonded to an alkyl group (R) and halogen X. It can be represented by the formula RMgX. A Grignard reagent is formed by the reaction of magnesium metal with haloalkane using dry ethoxyethane as a solvent . Ethoxyethane has a boiling point of 35c, forms a dense vapour and is highly flammable. A)give one reason why a hot water bath is used rather than direct heating with a Bunsen burner when preparing the Grignard reagent. B)Grignard reacts with water, suggest why the ethoxyethane protects the Grignard reagent from reacting with water vapour in air .

Scroll to see replies

Reply 1

username986184

Original post by usmsankhan

(edited 8 years ago)

Reply 2

usmsankhan

thanks so you would say that it is less dangerousness to use the water bath . Thanks so much . Really need help on part b also thanks !]

(edited 8 years ago)

Reply 3

usmsankhan

Original post by TeachChemistry

Urgent? Why what's kicking off?

Let's take part A. Question says ethoxyethane is highly flammable. A Bunsen burner gives a naked flame at about 800 degrees. What do you think they are looking for here?[so you would say it's less dangerous with water bath could you also pls help with party b thanks so much !]

Reply 4

username986184

Original post by usmsankhan

thanks so you would say that it is less dangerousness to use the water bath . Thanks so much . Really need help on part b also thanks !]

Question says that it 'forms a dense vapour'.

Reply 5

usmsankhan

Original post by TeachChemistry

Question says that it 'forms a dense vapour'.

So I don't understand what you would write would you say it's insoluble ?

Reply 6

username986184

Original post by usmsankhan

So I don't understand what you would write would you say it's insoluble ?

True that water and ether are not miscible but...
Think about DENSE vapour vs. water in air. Where is the Grignard reagent? What's on top of it? Does a DENSE vapour rise or fall?

Reply 7

usmsankhan

So dense water wouldn't rise right ? But I don't understand how this would come into the answer , sorry .

Reply 8

username986184

Original post by usmsankhan

So dense water wouldn't rise right ? But I don't understand how this would come into the answer , sorry .

I surrender.

The dense vapour on the Grignard reagent keeps moisture in the air out.

Reply 9

usmsankhan

Original post by TeachChemistry

I surrender.
Thanks
The dense vapour on the Grignard reagent keeps moisture in the air out.

Thanks so much lol it really helped

Reply 10

usmsankhan

Original post by usmsankhan

Thanks so much lol it really helped

Can I pls ask for help on 1 more question pls

Reply 11

username986184

Original post by usmsankhan

Can I pls ask for help on 1 more question pls

Of course. It's a public forum. :smile:

Reply 12

usmsankhan

The question is : why at first is the reaction of calcium with sulphuric acid faster than the reaction of magnesium with HCL ? This is a 2 point answer . For the first point I wrote that calcium is further down the group so is more reactive as it has a large atomic radi and less nuclear charge so would loss electrons more readily making it more reactive . But what would the second point be, really appreciated if u could help ?

Reply 13

username986184

Original post by usmsankhan

1. Number of H ions greater in sulphuric than HCl for same concentration
2. With sulphuric acid, the metal gets coated with insoluble calcium sulphate preventing the calcium from reacting. Calcium chloride is soluble so this problem doers not occur with hydrochloric acid

Reply 14

usmsankhan

Would my answer be correct for the first point ? Also calcium doesn't react with HCL it only reacts with sulphuric acid in the question its magnesium that reacts with HCL . Also how would having hydrogen ions make the reaction of sulphuric acid with calcium faster . Thanks btw

Reply 15

username986184

Original post by usmsankhan

Your reason is completely irrelevant here. If you do need to explain the relative reactivity of group 2 metals then you must say

less effective nuclear charge

and don't forget to mention shielding