in a chemical reaction, 5.2 grams of magnesium reacts with hydrogen nitrate. Calculate the amount of magnesium nitrate that is produced and the amount of hydrogen nitrate needed to react with the magnesium.

Answer 1

Mg + 2HNO3 ==> Mg(NO3)2 + H2

mols Mg = grams/molar mass
mols Mg(NO3)2 = mols Mg (look at the mole ratio) which is 1 mol Mg to 1 mol Mg(NO3)2.
Then grams Mg(NO3)2 = mols x molar mass.

For HNO3 needed,
convert mols Mg to mols HNO3 and convert mol HNO3 to grams as in the above.