Calculating the Amount of Product Formed from a Limiting Reactant The reaction is used to produce electricity in a hydrogen fuel cell. Suppose a fuel cell contains 150 g of H2(g) and 1500 g of O2(g) (each measured to two significant figures). How many grams of water can form? Molten gallium reacts with arsenic to form the semiconductor, gallium arsenide, GaAs, used in light-emitting diodes and solar cells : If 4.00 g of gallium is reacted with 5.50 g of arsenic, how many grams of the excess reactant are left at the end of the reaction? (a) 4.94 g As, (b) 0.56 g As, (c) 8.94 g Ga, or (d) 1.50 g As.
Answer : We have to calculate the amount of product formed from a limiting reactant The reaction is 2H2(g)+O2(g)2H2O(g). Step 1 We are asked to calculate the amount of a product, given the amounts of two reactants, so this is a limiting reactant problem.