1.4.2 Calculate the energy needed to turn 2,000 g of water, at 100°C into steam.
To calculate the energy needed to turn water into steam, we can use the formula:
\[ Q = m \cdot L \]
where:
- \( Q \) is the energy required (in joules),
- \( m \) is the mass of the water (in kilograms),
- \( L \) is the specific latent heat of vaporization (in joules per kilogram).
Given:
- Mass \( m = 2000 , \text{g} = 2 , \text{kg} \) (since 1,000 g = 1 kg),
- Specific latent heat of vaporization of water \( L = 2.3 \times 10^6 , \text{J/kg} \).
Now, substituting the values into the formula:
\[ Q = 2 , \text{kg} \times 2.3 \times 10^6 , \text{J/kg} = 4.6 \times 10^6 , \text{J} \]
So, the energy needed to turn 2,000 g of water at 100°C into steam is \( 4.6 \times 10^6 , \text{J} \) [3 marks].
1.4.3 Water has a high specific heat capacity.
Explain why this is useful when it is used as a coolant in car engines.
Water's high specific heat capacity means it can absorb a large amount of heat energy without a significant rise in temperature. This property is useful in car engines for the following reasons:
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Effective Heat Management: As the engine operates, it generates heat. Water can absorb this excess thermal energy efficiently, helping to maintain the engine at an optimal operating temperature, which prevents overheating.
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Stability in Temperature Fluctuations: The high specific heat capacity ensures that the coolant does not heat up too quickly, allowing for more stable temperature control within the engine, which is crucial for performance and longevity.
These properties help to protect the engine components from heat damage and contribute to the overall efficiency of the engine system.
3 answers