Answer:
i = 2.79
Explanation:
The excersise talks about the colligative property, freezing point depression.
Formula to calculate the freezing point of a solution is:
Freezing point of pure solvent - Freezing point of solution = m . Kf . i
Let's replace data given. (i = Van't Hoff factor, numbers of ions dissolved in solution)
48.1°C - 44°C = 0.15 m . 9.78°C/m . i
4.1°C / (0.15 m . 9.78°C/m) = i
i = 2.79
In this case, numbers of ions dissolved can decrease the freezing point of a solution, which is always lower than pure solvent.
Answer:
2023.04 g
Explanation:
Magnetite reacts with hydrogen to produce Iron metal and steam. Steam instead of water is produced as the reaction occurs at temperatures above the boiling point of water.
Fe₃O₄ + 4 H₂ → 3 Fe +4 H₂O
From the equation, 1 mole of Fe₃O₄ reacts with 4 moles of H₂.
69.76 grams of H₂ has the following number of moles.
Number of moles= mass/RAM
=69.76/2
=34.88 moles.
The reaction ratio of Fe₃O₄ to H₂ is 1:4
Thus number of moles of magnetite= (1×34.88)/4
=8.72 moles.
Mass= moles × molecular weight
=8.72 moles × (56×3+16×4)
=2023.04 grams
A is correct because there is no reaction involved
