Question

7 класс* Габриелян О Спараграф 14 №9 опыт*Пять чайных ложек повареной соли (полных,с горкой) растворите примерно в 450г (450 мл) воды.Учитывая,что масса соли в каждой ложке 10 грамм , расчитайте массовую долю соли в растворе. Возьмите две одинаковые пластиковые бутылки объемом 0,5 л.В 1-ую налейте полученный раствор,во 2-ую водопроводную воду. Поместите бутылки в морозильную камеру холодильника. Загляните в холодильник примерно через час. Какая жидкость начнет замерзать раньше? В какой бутылке содержимое раньше превратится в лед? Сделайте вывод! (это надо описать в виде сочинения) начало-я взял две бутылки итд

Answer 1

в виде сочинения сама напишешь. а начнет замерзать водопроводная вода. так как соль при растворении в воде  понижает температуру замерзания раствора. именно поэтому соль зимой разбрасывают по снегу, чтоб снизить температуру замерзания и не сильно скользило 

Answer 2

Problem Statement

The problem states that you need to calculate the mass fraction of salt in a solution and then conduct an experiment using two plastic bottles to determine which liquid freezes first. You are asked to write an essay describing the experiment and draw conclusions based on the results.

Calculating the Mass Fraction of Salt in the Solution

To calculate the mass fraction of salt in the solution, we need to know the mass of the salt and the mass of the solution.

Given: - 5 teaspoons of table salt (each teaspoon contains 10 grams of salt) - Approximately 450 grams (or 450 mL) of water

To calculate the mass fraction of salt, we need to divide the mass of the salt by the total mass of the solution (salt + water).

The mass of the salt can be calculated as follows: 5 teaspoons * 10 grams/teaspoon = 50 grams

The total mass of the solution is the sum of the mass of the salt and the mass of the water: 50 grams + 450 grams = 500 grams

Now, we can calculate the mass fraction of salt in the solution: Mass fraction of salt = (mass of salt / total mass of solution) * 100%

Mass fraction of salt = (50 grams / 500 grams) * 100% = 10%

Therefore, the mass fraction of salt in the solution is 10%.

Conducting the Experiment

To conduct the experiment, you need two identical plastic bottles with a volume of 0.5 liters (or 500 mL).

1. Pour the prepared salt solution into the first bottle. 2. Fill the second bottle with tap water.

Observing the Results

Place both bottles in the freezer compartment of the refrigerator. After approximately one hour, check the bottles to see which liquid freezes first.

Drawing Conclusions

Based on the results of the experiment, you can draw conclusions about the freezing point depression caused by the presence of salt in the solution.

Salt lowers the freezing point of water, which means that the saltwater solution will have a lower freezing point than pure water. As a result, the saltwater solution will take longer to freeze compared to the tap water.

Therefore, the tap water in the second bottle will freeze first, while the saltwater solution in the first bottle will remain in its liquid state for a longer period of time.

This experiment demonstrates the colligative property of solutions, where the presence of solute particles (in this case, salt) affects the physical properties of the solvent (water).

In conclusion, the mass fraction of salt in the solution was calculated to be 10%. The experiment showed that the tap water froze before the saltwater solution, confirming the freezing point depression caused by the presence of salt. This experiment highlights the importance of understanding the properties of solutions and how they can be altered by the addition of solutes.

Note: The information provided in this response is based on general scientific knowledge.