# How many grams of CaCl_2 can dissolve in 200 g of water at 10°C?

May 23, 2017

$128 {\text{gCaCl}}_{2}$ per $200 \text{gH"_2"O}$

#### Explanation:

You will need to refer to a solubility curve graph, which indicates how much of each solute will dissolve in $100 \text{g}$ water at indicated temperatures. A typical one looks like this:

We need to look at how much ${\text{CaCl}}_{2}$ will dissolve in $100 \text{g" "H"_2"O}$ at ${10}^{o} C$.

From the graph, the point of intersection between the ${\text{CaCl}}_{2}$ curve (the orange line) and the ${10}^{o} C$ line appears to occur at the point of roughly $64 \text{g}$ per $100 \text{g} {H}_{2} O$

This means that at ${10}^{o} C$, $64 {\text{gCaCl}}_{2}$ will dissolve in color(black)(100"gH"_2"O", but the question asks how much will dissolve in color(black)(200"gH"_2"O". This can be found simply enough by doubling the solubility at ${10}^{o} C$:

$64 {\text{gCaCl"_2 xx 2 = 128"gCaCl}}_{2}$.

So, $128 {\text{gCaCl}}_{2}$ will dissolve in $200 \text{gH"_2"O}$ at ${10}^{o} C$