Chemistry reactions?

Question

if 20g of Mg react with excess HCl how many grams of magnesium chloride are produced?

Answer 1

I do not have a periodic table handy, but I will give you the steps in solving this.

First, it is very important to balance the chemical reaction, which is
Mg + 2HCl ---> MgCl2 + H2(gas)

From this, one mole of Mg metal will produce one mole of Magnesium Chloride. Thus, divide 20g by the Atomic Mass of Mg. If I remember right it is about 24g/mole. So, it is approximately 0.83 mole of Magnesium. OR, 0.83 mole of MgCl2 ALSO.

Multiply this by the MOLAR Mass of MgCl2, which I believe is about 94, since each Chlorine is about 35g/mole.

Thus, .83 x 94 = about 78 g of MgCl2.

You can fine tune the calculations from data from your periodic table and your teacher's instructions on how many decimal places of the atomic masses are you going to use.

Answer 2

Equation =

Mg + 2HCl -> MgCl2 + H2

so one mole makes one mole of MgCl2

its 1:1 molecular ratio

Now heres the part you do.

Work out the molar masses of Mg and MgCl2
and then the number of moles in 25 g Mg

Then has 1 mole of Mg makes MgCl2

the solution is

The number of moles in 25 g Mg x the molar mass of MgCl2