PLEAS HELP :') ''If 5.6 mole of calcium metal is reacted, how many grams of calcium phosphide will form?'

340 grams Ca₃P₂ (2 sig. figs.)

Explanation:

   3Ca     +     2P     =>    Ca₃P₂

5.6 mole + excess =>   ? grams

Convert the 'known' to a coefficient of 1 by dividing all coefficients by 3.

=>  Ca   +   2/3P   =>    1/3Ca₃P₂

From the above, 1 mole of Ca => 1/3 mole Ca₃P₂  

∴ 5.6 mole Ca in an excess of P => 1/3(5.6 mole) Ca₃P₂

=> 1.8666 mol Ca₃P₂ (calculator answer) ≅ 1.9 mol Ca₃P₂

=> 1.9 mole x 182 g Ca₃P₂/mol Ca₃P₂ = 339.73333 grams Ca₃P₂

≅ 340 grams Ca₃P₂ (2 sig. figs.)