Answer:
-0.93 °C; 100.26 °C
Step-by-step explanation:
(a) Freezing point depression
The formula for the freezing point depression ΔT_f is
ΔT_f = iKf·b
i is the van’t Hoff factor: the number of moles of particles you get from a solute.
For sucrose,
Sucrose (s) ⟶ sucrose (aq)
1 mole sucrose ⟶ 1 mol particles i = 1
ΔT_f = 1 × 1.86 × 0.50
ΔT_f = 0.93 °C
T_f = T_f° - ΔT_f
T_f = 0.00 – 0.93
T_f = -0.93 °C
(b) Boiling point elevation
The formula for the boiling point elevation ΔTb is
ΔTb = iKb·b
ΔTb = 1 × 0.512 × 0.50
ΔTb = 0.256 °C
Tb = Tb° + ΔTb
Tb = 100.00 + 0.256
Tb = 100.26 °C
average atomic mass of Cu = 63.54
Explanation:
average atomic mass = atomic mass of isotope 1 × abundance of isotope 1 + atomic mass of isotope 2 × abundance of isotope 2 +...+ atomic mass of isotope n × abundance of isotope n
average atomic mass of Cu = atomic mass of Cu-63 × abundance of isotope Cu-63 + atomic mass of isotope Cu-65 × abundance of isotope Cu-65
average atomic mass of Cu = 62.93 × (69.17 / 100) + 64.93 × (30.83 / 100)
average atomic mass of Cu = 63.54
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average atomic mass
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Answer - B Atoms in the original substances are arranged in a different way to make new substances
