masses and percentage yield

[helloworld101]

hi am getting trouble solving this can u help me figure it out

what is the maximum mass of C6H2Cl3OH that ca be obtained from 10g of phenol C6H5OH? A chemist who carried out the conversion obtained 19.54g of the product. What percentage yield did he obtained?

[helloworld101]

what volume of hydrogen is formed when 3.0g of magnesium react with an excess of dilute sulphuric acid

plz help
thanks in advance

[Sonic]

what volume of hydrogen is formed when 3.0g of magnesium react with an excess of dilute sulphuric acid

plz help
thanks in advance

Assumptions:

The surroundings are at STP and remain so.
Hydrogen may be treated as an ideal gas


Mg + H2SO4 ---> MgSO4 + H2

From the balanced equation there is a molar ratio of 1:1 for Mg and H2. This means an equivalent number of moles will be produced for those used up.

You can find out the moles of Mg by dividing 3g by Mg's relative atomic mass (from your periodic table).

This will be equal to the moles of hydrogen formed because of the ratio above.

Use the fact that one mole of an ideal gas occupies 22.4dm^3 of space at STP and multiply by the answer obtained from the last sentence.


I find the answer to be 2.76dm^3 = 2.76L taking the relative atomic mass of Mg as 24.305g/mol

Post back if you need more help with the working

[helloworld101]

thank u so much. thanks