Question

При растворении едкого калия в воде образовалось 500 грамм раствора, температура которого повысилась на 7 градусов. Принимая энтальпию растворения едкого калия равной -58,5 кДж/моль, определите число грамм-эквивалентов КОН в полученном растворе

Answer 1

1. Найдем количество тепла, выделившегося при растворении щелочи:
Q=C*m*(t2-t1)=4,2кдж/кг*град*0,5кг*7град=14,7 кдж
2. при растворении 1 моля щелочи выделяется 58 кдж, 
при растворении х моль ---------                            14,7кдж
х=0,25 моль. Т.к. молярная и эквивалентная массы КОН равны, то nэ=0,25

Answer 2

Calculation of Gram-Equivalents of KOH in the Solution

To determine the number of gram-equivalents of KOH in the obtained solution, we need to use the concept of gram-equivalents. Gram-equivalents are a measure of the amount of a substance that can react with or replace one mole of hydrogen ions (H+).

The formula to calculate the number of gram-equivalents is:

Gram-Equivalents = (Mass of Substance) / (Equivalent Mass)

In this case, we have 500 grams of the solution and the temperature increased by 7 degrees Celsius. We are given the enthalpy of dissolution of KOH as -58.5 kJ/mol.

To calculate the number of gram-equivalents of KOH, we need to find the equivalent mass of KOH. The equivalent mass is the molar mass divided by the number of equivalents per mole.

The molar mass of KOH is: - Potassium (K): 39.1 g/mol - Oxygen (O): 16.0 g/mol - Hydrogen (H): 1.0 g/mol

So, the molar mass of KOH is 39.1 + 16.0 + 1.0 = 56.1 g/mol.

Now, we need to find the number of equivalents per mole of KOH. Since KOH is a strong base, it can donate one hydroxide ion (OH-) per molecule. Therefore, the number of equivalents per mole of KOH is 1.

Using the formula mentioned earlier, we can calculate the number of gram-equivalents of KOH:

Gram-Equivalents = (Mass of Substance) / (Equivalent Mass) **Gram-Equivalents = 500 g / (56.1 g