The Student Room Group

AS question

1.

When 0.28g of a basic oxide, MO, is reacted with 250cm3 of 0.05moldm–3 hydrochloricacid the excess acid required 50cm3 of 0.05moldm–3 sodium hydroxide solution forneutralisation. Which one of the following is the relative atomic mass of M?

I ended up getting 56 for the RAM but it was wrong.

Can anyone help?

Scroll to see replies

What's the answer?
Also, did you minus 16 for the oxygen on the oxide?
(edited 7 years ago)
Reply 2
Original post by ozmo19

1.

When 0.28g of a basic oxide, MO, is reacted with 250cm3 of 0.05moldm–3 hydrochloricacid the excess acid required 50cm3 of 0.05moldm–3 sodium hydroxide solution forneutralisation. Which one of the following is the relative atomic mass of M?

I ended up getting 56 for the RAM but it was wrong.

Can anyone help?


Are you given a balanced equation at all?

And what is the actual answer given? Could it be that you didnt subtract 16 (Mr of Oxygen) from the 56?
Reply 3
Original post by derpz
Are you given a balanced equation at all?

And what is the actual answer given? Could it be that you didnt subtract 16 (Mr of Oxygen) from the 56?


The answer was 40.. after all the working out it looks like i forgot to -16.

Thanks
Reply 4
Original post by MrFartFace
What's the answer?
Also, did you minus 16 for the oxygen on the oxide?


Original post by derpz
Are you given a balanced equation at all?

And what is the actual answer given? Could it be that you didnt subtract 16 (Mr of Oxygen) from the 56?

1.

3.12 g of MCl2 were dissolved in water and made up to one litre of solution. 25.0 cm3 of thissolution reacts with 7.5cm3 of 0.100M silver nitrate solution.
Which group 2 element is M?

The answer is Barium and i not sure how to find that?

Reply 5
Original post by ozmo19

1.

3.12 g of MCl2 were dissolved in water and made up to one litre of solution. 25.0 cm3 of thissolution reacts with 7.5cm3 of 0.100M silver nitrate solution.
Which group 2 element is M?

The answer is Barium and i not sure how to find that?



I'll have a go, is it 0.100moles or is that the concentration? Also, are you given an equation?
Reply 6
Hi! I was looking at electronic configuration of chromiumScreenshot_2016-04-01-22-50-44.jpeg . I wanted to know why is last electon in s subshell, when d have only 5 electrons, having a capacity of 10.
Original post by Noshervan
Hi! I was looking at electronic configuration of chromiumScreenshot_2016-04-01-22-50-44.jpeg . I wanted to know why is last electon in s subshell, when d have only 5 electrons, having a capacity of 10.


Read this.


http://www.chemguide.co.uk/atoms/properties/3d4sproblem.html#top
Reply 8
Original post by Noshervan
Hi! I was looking at electronic configuration of chromiumScreenshot_2016-04-01-22-50-44.jpeg . I wanted to know why is last electon in s subshell, when d have only 5 electrons, having a capacity of 10.


Chromium and Copper are anomalies when it comes to electronic arrangement, one of their electrons from the d sublevel is donated to the s sublevel which is known as "electron promotion" - this only occurs with Copper and Chromium!
Original post by derpz
Chromium and Copper are anomalies when it comes to electronic arrangement, one of their electrons from the d sublevel is donated to the s sublevel which is known as "electron promotion" - this only occurs with Copper and Chromium!


4s fills before the 3d, at least at this level. With the exception of copper and chromium the transition metals in that row have 2 electrons in the 4s
Original post by derpz
Chromium and Copper are anomalies when it comes to electronic arrangement, one of their electrons from the d sublevel is donated to the s sublevel which is known as "electron promotion" - this only occurs with Copper and Chromium!


They are not really anomalies. If you read the article in the link that I posted it all becomes clear. There is no 'electron promotion'. The 4s1 is the lowest energy electron configuration for that metal. Other d-block metals in the other periods do this too.
Original post by samb1234
4s fills before the 3d, at least at this level. With the exception of copper and chromium the transition metals in that row have 2 electrons in the 4s


Read the article in the link I posted.
Original post by TeachChemistry
Read the article in the link I posted.


I know, its not what really is going on but tbh for the sort of questions they ask at a level the explanation they give for things like chromium and copper is the same explanation that appears on the mark schemes, so unfortunately even though its not really true just have to go along with it to a certain extent



Thanks for the link, problem solved.
Original post by ozmo19

1.

When 0.28g of a basic oxide, MO, is reacted with 250cm3 of 0.05moldm–3 hydrochloricacid the excess acid required 50cm3 of 0.05moldm–3 sodium hydroxide solution forneutralisation. Which one of the following is the relative atomic mass of M?

I ended up getting 56 for the RAM but it was wrong.

Can anyone help?


Whats the working please
Original post by ozmo19

1.

3.12 g of MCl2 were dissolved in water and made up to one litre of solution. 25.0 cm3 of thissolution reacts with 7.5cm3 of 0.100M silver nitrate solution.
Which group 2 element is M?

The answer is Barium and i not sure how to find that?



Whats the working please?
HI! i just saw a question what is the observation when sulphuric acid is added to potassium chloride and the fumes made are passed through potasium iodide solution. the answer is a colorles solution forms. i want to ask why doesn`t the chlorine in HCl produced displace iodine in potasium iodide and form a brown solution.
Original post by Noshervan
HI! i just saw a question what is the observation when sulphuric acid is added to potassium chloride and the fumes made are passed through potasium iodide solution. the answer is a colorles solution forms. i want to ask why doesn`t the chlorine in HCl produced displace iodine in potasium iodide and form a brown solution.


Because it's not chlorine it's chloride.
Original post by TeachChemistry
Because it's not chlorine it's chloride.

But chloride ion is more reaxtive than iodide ion and it should displace iodine from potassium iodide
Original post by Noshervan
But chloride ion is more reaxtive than iodide ion and it should displace iodine from potassium iodide


Chlorine is more reactive than iodine.

Chloride is not more reactive than iodide.

Chlorine would react with iodide to give chloride and iodine. But you do not have chlorine - you have chloride.

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