Answer:
Temperature of freezing for the solution is. 3.3°C
Explanation:
This is an excersise of coligative property (freezing low depression)
ΔT = Kf . m
Mass of solute (biphenyl) → 0.617 g
Mass of solvent (cycloexane) → 25 g
m = molality (mol of solute in 1kg of solvent)
Let's find out moles of solute:
Moles = Mass / Molar mass
Moles = 0.617 g / 154 g/m → 0.004 moles
To know molalilty, let's convert 25 g to kg
25 g = 0.025 kg
moles / kg = molality
0.004 m / 0.025 kg = 0.16m
ΔT = T°freezing pure solvent - T° freezing solution
6.5°C - T° freezing solution = 20°C/m . 0.16m
6.5°C - T° freezing solution = 3.20°C
6.5°C - 3.20°C = T° freezing solution → °3.3 °C
Explanation:
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Answer:
D
Explanation:
Just look at the groups and their tendencies. Or look at their electron configurations. You will notice that calcium has 2 valence electrons and bromine has 7 valence electrons.
Halogens have the most valence electrons possible without completing a shell (8 would be needed for that)
The answer is b. releases H+ ion in water.
117 mL of 0.210 M K₂S solution
Explanation:
The question asks about the volume of 0.210 M K₂S (potassium sulfide) solution required to completely react with 175 mL of 0.140 M Co(NO₃)₂ (cobalt(II) nitrate).
We have the chemical reaction:
K₂S + Co(NO₃)₂ → CoS + 2 KNO₃
molar concentration = number of moles / volume (L)
number of moles = molar concentration × volume
number of moles of Co(NO₃)₂ = 0.140 × 175 = 24.5 mmoles
We see from the chemical reaction that 1 mmole of Co(NO₃)₂ is reacting with 1 mmole of K₂S, so 24.5 mmoles of Co(NO₃)₂ are reacting with 24.5 mmoles of K₂S.
volume = number of moles / molar concentration
volume of K₂S solution = 24.5 / 0.210 = 117 mL
Learn more about:
molar concentration
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