Question

какое количество (моль) фосфорной кислоты должно прореагировать с 4 % - ным раствором гидрооксида калия массой 250 грамм до образования фосфата калия.

Answer 1

H3PO4+K(OH)=250/4==62.5 моль
K(OH)=250X4=1000моль=103кмоль

Answer 2

m(KOH) = 250*0,04=10 грамм.
M(KOH)=56 г/моль
M(H3PO4)=98 г/моль.

10г.-----Хг.
KOH + H3PO4 = KH2PO4 + H2O
56 г.-----98г.

Х=17,7 грамм. 

Answer 3

Calculation of the Amount of Phosphoric Acid

To determine the amount of phosphoric acid (H3PO4) that will react with a 4% potassium hydroxide (KOH) solution weighing 250 grams to form potassium phosphate (K3PO4), we need to use stoichiometry and the balanced chemical equation for the reaction.

The balanced chemical equation for the reaction between phosphoric acid and potassium hydroxide is:

3 H3PO4 + 6 KOH → K3PO4 + 6 H2O

From the balanced equation, we can see that 3 moles of phosphoric acid react with 6 moles of potassium hydroxide to produce 1 mole of potassium phosphate.

To calculate the amount of phosphoric acid needed, we can use the following steps:

Step 1: Calculate the number of moles of potassium hydroxide: Given that the mass of the potassium hydroxide solution is 250 grams and the concentration is 4%, we can calculate the mass of potassium hydroxide (KOH) in the solution:

Mass of KOH = 4% * 250 grams = 0.04 * 250 grams = 10 grams

Next, we need to calculate the number of moles of potassium hydroxide using its molar mass:

Molar mass of KOH = 39.10 g/mol (potassium) + 16.00 g/mol (oxygen) + 1.01 g/mol (hydrogen) = 56.11 g/mol

Number of moles of KOH = Mass of KOH / Molar mass of KOH = 10 grams / 56.11 g/mol = 0.178 moles

Step 2: Calculate the number of moles of phosphoric acid: From the balanced equation, we know that 3 moles of phosphoric acid react with 6 moles of potassium hydroxide. Therefore, the ratio of moles of phosphoric acid to moles of potassium hydroxide is 3:6 or 1:2.

Number of moles of H3PO4 = (1/2) * Number of moles of KOH = (1/2) * 0.178 moles = 0.089 moles

Therefore, the amount of phosphoric acid (H3PO4) that should react with the 4% potassium hydroxide solution weighing 250 grams to form potassium phosphate (K3PO4) is approximately 0.089 moles.

Please note that the calculation assumes that the reaction goes to completion and that the concentration of the phosphoric acid is 100%. In reality, the reaction may not go to completion, and the concentration of the phosphoric acid may vary.