Chemistry A lvl -Moles problem

[HM.RABBI]

Guys can u explain the circled red part ??????
I mean why the percentage is obtained by multiplying by Mr....It only gives the mass of copper not the ratio
Shouldn't it be [ (Mass of Cu)/ mass of leech sol ] * 100%
but "mass of leech sol " is not given
Can anyone explain

 

[CoNfUsEd1]

In A level, u r often supposed to use the assumption that aqueous solutions have a density approximately equal to that of water..... so the density being 1.0 g/cm3, it becomes that 50cm3 of the leech solution has mass 50 g....
u r supposed to use this assumption often in paper 3 also, in the equation E=mc (delta T) in the thermochemistry part.. instead of mass, u are supposed to use the volume in the same equation to find out the enthalpy change during practicals!

 

[HM.RABBI]

In A level, u r often supposed to use the assumption that aqueous solutions have a density approximately equal to that of water..... so the density being 1.0 g/cm3, it becomes that 50cm3 of the leech solution has mass 50 g....
u r supposed to use this assumption often in paper 3 also, in the equation E=mc (delta T) in the thermochemistry part.. instead of mass, u are supposed to use the volume in the same equation to find out the enthalpy change during practicals!

Understood Thax