Sodium reacts with oxygen to produce sodium oxide. 4Na(s) + O2(g) - - 2Na2O(s)
a. How many grams of Na20 are produced when 57.5 g of Na
reacts ?
b. If you have 18.0 g of Na, how many grams of O2 are
required for reaction?
c. How many grams of O2 are needed in a reaction that
produces 75.0 g of Na2O?

Explanation:

a )

4Na(s) + O₂(g) - - 2Na₂O(s)

4 x 23g    32g           2x62

92 g of Na produces 124 g of Na₂O(s)

57.5 g of Na produces (124 / 92) x 57.5

= 77.5 g of Na₂O(s)

b )

92 g of Na requires 32 g of O₂

18 g of Na requires ( 32 / 92 ) x 18

= 6.26 g of O₂

c )

128 g of Na₂O(s) requires 32 g of O₂

75 g of Na₂O(s) requires ( 32 / 128 ) x 75

= 18.75 g of O₂

a:

by the combination of an unlimited number of elements

i think that the answer is c