Question

1. (a) state any three 1. uses of herbs in a community, 2. disadvantages of using herbs. 6 (b) fig. 10.1 shows a separation technique. (i) name 1. the separation technique shown, 2. component x. 2 (ii) state the function of x. 1 (iii) describe and explain the principle of this technique. 2 (c) ammonia gas reacts with dilute hydrochloric acid to form ammonium chloride. nh₃ + hcl -> nh₄cl (i) write a balanced chemical equation for the reaction. 1 (ii) name this type of reaction. 1 (iii) calculate the amount of ammonium chloride produced, given that 8.5 g of ammonia was used up. 2

Explanation:

Step1: Answer (a) - Uses of herbs

Herbs can be used for medicinal purposes (e.g., echinacea for immune - boost), culinary purposes (e.g., basil in cooking), and as natural pesticides (e.g., neem). Disadvantages include potential allergic reactions, variability in potency, and some may be toxic in large amounts.

Step2: Answer (b)(i)

1. The separation technique is distillation.
2. Component X is a condenser.

Step3: Answer (b)(ii)

The function of the condenser is to cool the vapor back into a liquid.

Step4: Answer (b)(iii)

The principle of distillation is based on the different boiling points of components in a mixture. The component with the lower boiling point vaporizes first, is then condensed back to a liquid by the condenser and collected.

Step5: Answer (c)(i)

The balanced chemical equation is $NH_3 + HCl
ightarrow NH_4Cl$.

Step6: Answer (c)(ii)

This is a combination reaction.

Step7: Answer (c)(iii)

The molar mass of $NH_3$ is $M_{NH_3}=14 + 3\times1=17\ g/mol$. The number of moles of $NH_3$, $n_{NH_3}=\frac{8.5\ g}{17\ g/mol}=0.5\ mol$. From the balanced equation, the mole ratio of $NH_3$ to $NH_4Cl$ is 1:1. The molar mass of $NH_4Cl$ is $M_{NH_4Cl}=14 + 4\times1+35.5 = 53.5\ g/mol$. The mass of $NH_4Cl$ produced, $m_{NH_4Cl}=n\times M = 0.5\ mol\times53.5\ g/mol = 26.75\ g$.

Answer:

(a)

1. Medicinal, culinary, natural pesticides.
2. Allergic reactions, variable potency, potential toxicity.

(b)(i)

1. Distillation
2. Condenser

(b)(ii) Cools vapor to liquid.
(b)(iii) Based on different boiling - points of mixture components; lower - boiling component vaporizes first, then is condensed.
(c)(i) $NH_3 + HCl
ightarrow NH_4Cl$
(c)(ii) Combination reaction
(c)(iii) 26.75 g