A rail terminal receives aqueous ammonia for a nearby chemical factory. Fig. 1 shows a rail tanker connected to a closed unloading line and a small water se...
Question 1 Report
A rail terminal receives aqueous ammonia for a nearby chemical factory. Fig. 1 shows a rail tanker connected to a closed unloading line and a small water seal. Before unloading, an operator checks the tanker mass. After unloading, the difference in mass gives the mass of ammonia solution transferred. Table 1 shows measurements from one delivery. The factory uses ammonia solution to make cleaning products.
| Measurement | Value |
|---|---|
| Tanker mass before unloading / kg | 64 820 |
| Tanker mass after unloading / kg | 49 570 |
| Ammonia concentration / % by mass | 25.0 |
(a) Use Table 1 to calculate the mass of solution transferred. [2]
(b) Give the mass of ammonia in 100 g of this solution. [1]
(c) Suggest why the unloading line is closed rather than open to air. [1]
(d) Name the type of substance formed when ammonia dissolves in water. [1]
(e) Give one use of ammonia solution in the factory. [1]
Answer Details
(a) The mass transferred is the decrease in tanker mass:
\[64\,820\text{ kg}-49\,570\text{ kg}=15\,250\text{ kg}\]
The mass of solution transferred is 15 250 kg. [2]
(b) A 25.0% by mass solution contains 25.0 g of ammonia in every 100 g of solution. [1]
(c) The unloading line is closed to prevent ammonia gas escaping, which would cause air pollution and a safety hazard. [1]
(d) When ammonia dissolves in water it forms an alkali, or alkaline solution. [1]
(e) One use is making cleaning products or detergents. [1]
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