Question #bbb64

Question

1622 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2014-06-06T00:18:28

The final concentration of the solution is 0.35 mol/L.

Method 1

One way to calculate the concentration of a diluted solution is to use the formula

#c_1V_1 = c_2V_2#

#c_1# = 12.0 mol/L; #V_1# = 35 mL = 0.035 L
#c_2# = ?; #V_2# = 1.20 L

Solve the formula for #c_2#.

# c_2 = c_1 × V_1/V_2# = 12.0 mol/L × #(0.035"L")/(1.20"L")# = 0.35 mol/L

Method 2

Remember that the number of moles is constant.

#n_1 = n_2#

#n_1 = c_1V_1# = #(12.0"mol")/(1"L")# × 0.035 L = 0.42 mol

#n_2 = c_2V_2 = n_1# = 0.42 mol

#c_2 = n_2/V_2 = (0.42"mol")/(0.1.20"L")# = 0.35 mol/L

This makes sense. You are increasing the volume by a factor of about 30. So the concentration should decrease by a factor of about 30.

#12.0/30# = 0.4