Question

when carbon is burned in air, it reacts with oxygen to form carbon dioxide. when 19.2 g of carbon were burned in the presence of 68.0 g of oxygen, 16.8 g of oxygen remained unreacted. what mass of carbon dioxide was produced? express your answer to one decimal place and include the appropriate units.

Explanation:

Step1: Calculate mass of oxygen reacted

The initial mass of oxygen is 68.0 g and 16.8 g remained un - reacted. So the mass of oxygen that reacted, $m_{O_2\ reacted}=68.0\ g - 16.8\ g$.
$m_{O_2\ reacted}=51.2\ g$

Step2: Use law of conservation of mass

According to the law of conservation of mass, in a chemical reaction, the total mass of reactants is equal to the total mass of products. The reactants are carbon and oxygen, and the product is carbon dioxide.
The mass of carbon is $m_{C}=19.2\ g$ and the mass of oxygen that reacted is $m_{O_2\ reacted}=51.2\ g$.
The mass of carbon dioxide produced, $m_{CO_2}=m_{C}+m_{O_2\ reacted}$.
$m_{CO_2}=19.2\ g + 51.2\ g=70.4\ g$

Answer:

$70.4\ g$