80 g of K2Cr2O7 was dissolved in 500 ml of water to determine C%, N, M g / l of the resulting solution.

1. The percentage concentration of the solution is calculated by the formula:

W (K2Cr2O7) = m / mr-pa • 100%.

Let us determine the mass of the solution, since the density of water is 1 g / ml, then the mass of water = volume.

mr-pa) = m (K2Cr2O7) + m (H2O) = 80 + 500 = 580 g.

W (K2Cr2O7) = 80/580 • 100% = 13.79%.

2. The number of molecules is determined by the formula:

N = Na • n.

Na is Avogadro’s number 6.022 10 ^ 23 mol − 1.

n (K2Cr2O7) = m / M = 80 / 294.19 = 0.272 mol.

N = 6.022 · 10 ^ 23 · 0.272 = 1.64 · 10 ^ 23 mol.

The molar concentration of a solution is expressed by the formula:

C = m / (M • V) = 80 / 294.19 • 580 = 0.4689 g / l.