WAEC - Chemistry (2016 - No. 7)
The mass of potassium hydroxide required to make 300.ocm3 of 0.4 moldm-3 solution is {KOH = 56.0}
26.88g
13.44g
6.72g
3.36g
설명
300cm3 of 0.4moldm3
1000cm3 contains 0.4mole
300cm3 will contain \(\frac{300 \times 0.4}{1000}\)
= 0.12mole
Number of moles = \(\frac{Mass}{\text {Molecular mass}}\)
Mass = number of moles x m.mass
= 0.12 x 56 = 6.72g
1000cm3 contains 0.4mole
300cm3 will contain \(\frac{300 \times 0.4}{1000}\)
= 0.12mole
Number of moles = \(\frac{Mass}{\text {Molecular mass}}\)
Mass = number of moles x m.mass
= 0.12 x 56 = 6.72g