भौतिक रसायन

The balanced chemical equation for the catalytic decomposition of ammonia is:

• The rate of reaction in terms of disappearance and appearance is:
  $$\text{Rate} = -\frac{1}{2}\frac{d[\text{NH}_3]}{dt} = \frac{d[\text{N}_2]}{dt} = \frac{1}{3}\frac{d[\text{H}_2]}{dt}$$
• For a zero order reaction, $\text{Rate} = k = 2.5 \times 10^{-4}\text{ mol L}^{-1}\text{ s}^{-1}$.
• Therefore, the rate of production of $\text{H}_2$ is:
  $$\frac{d[\text{H}_2]}{dt} = 3 \times \text{Rate} = 3 \times k = 3 \times (2.5 \times 10^{-4}) = 7.5 \times 10^{-4}\text{ mol L}^{-1}\text{ s}^{-1}$$

Gold number is defined as the minimum mass in milligrams of a protective colloid required to prevent coagulation of $10\text{ mL}$ of a standard gold sol on adding $1\text{ mL}$ of $10\%\text{ NaCl}$ solution.

Smaller gold number means greater protective power. Colloid A has the smallest gold number range ($0.005 - 0.01$, characteristic of gelatin), making it the most effective protective colloid.

The minimum concentration of an electrolyte in millimoles per litre (${\text{mmol L}}^{-1}$) required to cause precipitation or coagulation of a colloidal solution in two hours is defined as the coagulating value (or flocculation value) of the electrolyte. The smaller the coagulating value, the greater is the coagulating power of the electrolyte.