Answer:
Ag
Explanation:
To determine which element will displace hydrogen from a dilute acid, we need to make reference to the activity series or the electrochemical series. The activity series is a list of metallic ions according to their electropositivity.
This means elements are ranked here based on how electrically positive they are. Hence, an element above another element is relatively more electropositive than the one under it. For example calcium is less electropositive compared to sodium as calcium is found under sodium in the list.
Now, for an element to displace hydrogen, it means the particular element is more electropositive than hydrogen on the activity series. All the elements in the options are in a greater position relative to hydrogen on the activity series except silver. This means it cannot displace hydrogen from a dilute mineral acid
When it comes to physical changes like phase changes, there are two types of heat energy: sensible heat and latent heat. Sensible heat is the heat absorbed/released when you heat the substance but it doesn't change phase. An example would be heating lukewarm water. The substance is liquid all throughout. Latent heat, on the other hand, is the heat absorbed/released when there is a phase change. An example would be boiling water, because it changes liquid to vapor.
Hence, for freezing liquid, you use the latent heat, specifically the heat of fusion. The answer should be
2.5 g * (1 mol/18.02 g) * 6.03 kJ/mol = 0.84 kJ/mol
The answer is not in the choices. You only use Hvap if you boil water.
Answer:
5230J
Explanation:
Mass (m) = 250g
Initial temperature (T1) = 25°C
Final temperature (T2) = 30°C
Specific heat capacity (c) = 4.184J/g°C
Heat energy (Q) = ?
Heat energy (Q) = Mc∇T
Q = heat energy
M = mass of the substance
C = specific heat capacity
∇T = change in temperature = T2 - T1
Q = 250 × 4.184 × (30 - 25)
Q = 1046 ×5
Q = 5230J
The heat energy required to raise the temperature of 250g of water from 25°C to 30°C is 5230J
