Question

Just need the formulas and the way to solve the solution.

Answer 1

We are requested to solve the concentration of the solutions given.

The unit of concentration is given as M which can also be written as mol/L.

From the first question, let us calculate the number of moles of CaCl₂ in the solution.

Number of moles = mass /molar mass

$n=\frac{mass}{molar\text{ mass}}$

mass = 277.5g

molar mass can be calculated as

$\text{CaCl}_2=40+(35.5\cdot2)=40+70=110\text{ g/mol}$

Let's proceed to solve for the number of moles

$\begin{gathered} n=\frac{\text{mass}}{\text{molarmass}} \\ n=\frac{40}{110} \\ n=0.3636 \end{gathered}$

Using this number of moles, we can calculate the concentration of the solution.

C = n/V

c = concentration

n = number of moles

v = volume

substituting the values and solving for concentration

$\begin{gathered} c=\frac{n}{v} \\ n=0.3636 \\ v=2L \\ c=\frac{0.3636}{2} \\ c=0.1818M \end{gathered}$

The concentration of CaCl₂ is 0.1818M

b

From dilution formula,

$c_1v_1=c_2v_2$

where c and v represents the concentration and volume respectively.

Let's write out the values and solve for the concentration.

$\begin{gathered} c_1=0.1818M \\ v_1=50mL \\ v_2=250mL \\ c_2=\text{?} \end{gathered}$

substituting the values and solving for c2

$\begin{gathered} C_1V_1=C_2V_2 \\ 0.1818\times0.05=C_2\times0.25 \\ C_2=0.3636M \end{gathered}$

The new concentration is 0.3636M

NB; I converted the volumes from mL to L, but you don't need to and can simply plug in the values just as they have been given and you would get the same answer.

c.

Let's solve for concentration of solution B in 100ml beaker.

Using dilution formula

$\begin{gathered} c_1=0.3636M \\ v_1=250mL \\ v_2=100mL \\ c_2=\text{?} \end{gathered}$

Substitute the values and solve for C2

$\begin{gathered} C_1V_1=C_2V_2_{} \\ 0.3636\times250=C_2\times100_{} \\ C_2=0.909M \end{gathered}$

From the calculations above, the concentrations are 0.1818M, 0.3636M and 0.909M respectively.