How many grams of calcium are required to free 8 grams of hydrogen gas from hydrochloride acid, HCl?

The answer to your question is 160 g of Calcium

Explanation:

Data

mass of Calcium = ?

mass of Hydrogen = 8 g

reactant = HCl

Process

1.- Write the balanced chemical reaction

             Ca  + 2HCl   ⇒   CaCl₂  +  H₂

2.- Look for the atomic number of Calcium and hydrogen

Calcium = 40 g

Hydrogen = 1 x 2 = 2 g

3.- Use proportions to calculate the mass of calcium needed.

            40 g of Calcium 2 g of hydrogen

               x                       8 g of hydrogen

                         x = (8 x 40) / 2

                         x = 320/2

                         x = 160 g of Calcium

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

the answer is na (sodium)