Question

ЗАДАЧА вычислите количество вещества, соответствующее 4,9 г. фосфорной кислоты

Answer 1

N=m/M
M(H3PO4)= 1*3 + 31 + 16*4=98 
n(H3PO4)=4.9/98=0.05моль

Answer 2

Calculating the Amount of Substance of Phosphoric Acid

To calculate the amount of substance corresponding to 4.9 g of phosphoric acid, we can use the formula:

Amount of substance (in moles) = Mass / Molar mass

The molar mass of phosphoric acid (H3PO4) can be calculated by adding the atomic masses of its constituent elements: hydrogen (H), phosphorus (P), and oxygen (O).

Calculation

Using the molar masses of the elements: - Hydrogen (H): 1.007 g/mol - Phosphorus (P): 30.974 g/mol - Oxygen (O): 15.999 g/mol

The molar mass of phosphoric acid (H3PO4) is: ``` Molar mass = (3 * molar mass of H) + molar mass of P + (4 * molar mass of O) = (3 * 1.007 g/mol) + 30.974 g/mol + (4 * 15.999 g/mol) = 3.021 g/mol + 30.974 g/mol + 63.996 g/mol = 97.991 g/mol ```

Now, we can calculate the amount of substance: ``` Amount of substance = 4.9 g / 97.991 g/mol ≈ 0.050 moles ```

Therefore, the amount of substance corresponding to 4.9 g of phosphoric acid is approximately 0.050 moles.