What mass of salt (NaCl) should you add to 1.00 L of water in an
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Question

What mass of salt (NaCl) should you add to 1.00 L of water in an
ice cream maker to make a solution that freezes at -10.0 °C?
Assume complete dissociation of the NaCl and density of 1.00 g>mL for water.

Accepted Answer

Hi everyone here we have a question asking us to calculate the mass of potassium chloride that must be added to a 1.50 liter of water so that the solution freezes at negative 6.50°C Assume that potassium chloride completely dissociates in the solution. In the density of water is 1.0 g per meal leader. So water is our solvent, meaning that our freezing point constant Is 1.86 degrees Celsius per morality, and the freezing point of our solvent Is 0°C. The change in to freezing point equals the freezing point of our peer solvent minus the freezing point of our solution and the change in freezing point equals r. Van Hoff factor times our freezing point constant times our morality. The change in freezing point constant Equals 0°C minus -6.50°C Which equals 6.50°C. And our Van Hoff factor of potassium chloride if it completely dissociates is to. So our morality is going to equal the change in our freezing point, divided by our van Hoff factor times are freezing point constant, So our morality is going to equal 6.50°C divided by two Times 1.86°C per morality, Which equals 1.75 Morality morality equals moles over kilograms. So our morality Equals 1.74 moles per kilogram. And now we have to calculate the mass of potassium chloride. So the molar mass of potassium chloride equals .0983 g per mole plus 35 .45 - seven g per mole. That equals .551 g per mole. So our mass Equals 1.50 l Times one mil liter over 10 to the negative. Third. Leaders, times one g per mil, leader Times 1. moles per kilogram times one kg Over 10 to the 3rd g, Times 74.551 g over one mole. And our leaders are canceling out. Our male leaders are canceling out. Our grams are canceling out are kilograms are canceling out and our moles are canceling out, Leaving us with 195 g a potassium chloride. And that is our final answer. Thank you for watching. Bye.

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