# In the reaction: A + B -> C, if 4.2 grams of A react to make 6.8 grams of C, then how many grams of B were reacted?

Jan 25, 2017

The mass of $\text{B}$ reacted was 2.6 g.

#### Explanation:

We can use the Law of Conservation of Mass to solve the problem.

$\underbrace{\text{A")_color(red)("4.2 g") + underbrace("B")_color(red)(x) → underbrace("C")_color(red)("6.8 g}}$

$\text{4.2 g"color(white)(l) + x = "6.8 g}$

$x = \text{6.8 g - 4.2 g" = "2.6 g}$