Question

Вычислите какое количество вещества дигидрата гидрофосфата натрия NA2HPO4*2H2O следует растворить в 5 моль воды , чтобы получить раствор с массовой долей 20% безводной соли. если можно , пожалуйста с решением

Answer 1

M (Na2HPO4)=1000х5/95=52,63(г) 
M(Na2HPO4*2H2O )=178г/моль 
178г Na2HPO4*2H2O)содержит 142г Na2HPO4 
Хг---->-52,63г 
Х=65,97г 
n ( Na2HPO4*2H2O )=65,97/178=0,37(моль)

Answer 2

Calculation of the Amount of Sodium Hydrogen Phosphate Dihydrate (Na2HPO4*2H2O) to Dissolve in 5 Moles of Water

To calculate the amount of sodium hydrogen phosphate dihydrate (Na2HPO4*2H2O) that needs to be dissolved in 5 moles of water to obtain a solution with a mass fraction of 20% anhydrous salt, we need to consider the molar mass and stoichiometry of the compound.

The molar mass of Na2HPO4*2H2O can be calculated by summing the atomic masses of its constituent elements: - Sodium (Na): 22.99 g/mol - Hydrogen (H): 1.01 g/mol - Phosphorus (P): 30.97 g/mol - Oxygen (O): 16.00 g/mol

Using these values, we can calculate the molar mass of Na2HPO4*2H2O as follows: Molar mass of Na2HPO4*2H2O = (2 * Na) + P + (4 * O) + (2 * (2 * H + O)) = (2 * 22.99) + 30.97 + (4 * 16.00) + (2 * (2 * 1.01 + 16.00)) = 45.98 + 30.97 + 64.00 + (2 * 18.02) = 45.98 + 30.97 + 64.00 + 36.04 = 176.99 g/mol

To calculate the amount of Na2HPO4*2H2O needed to dissolve in 5 moles of water, we need to consider the stoichiometry of the compound. From the chemical formula, we can see that for every 1 mole of Na2HPO4*2H2O, we have 2 moles of water.

Therefore, the molar ratio of Na2HPO4*2H2O to water is 1:2.

To calculate the moles of Na2HPO4*2H2O needed, we can use the following equation: Moles of Na2HPO4*2H2O = (moles of water) / 2

Given that we have 5 moles of water, we can calculate the moles of Na2HPO4*2H2O as follows: Moles of Na2HPO4*2H2O = 5 / 2 = 2.5 moles

Therefore, to obtain a solution with a mass fraction of 20% anhydrous salt, we need to dissolve 2.5 moles of Na2HPO4*2H2O in 5 moles of water.

I hope this helps! Let me know if you have any further questions.