Explanation:
The reason as to why the dark chocolate always melted the fastest was because of it's colour. It was a darker shade than the milk and white chocolate and the sun naturally absorbs dark colours therefore it melted faster.

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Answer:
HCl acts as an excess reagent
Explanation:
The reaction equation is;
PbO + 2HCl → PbCl2 + H20
Number of moles of PbO = 13g/223.2 g/mol = 0.058 moles
Since the mole ratio is 1:1, 0.058 moles of PbCl2 is produced
Number of moles of HCl = 6.4 g/36.5g/mol = 0.175 moles
2 moles of HCl yields 1 mole of PbCl2
0.175 moles yields 0.175 moles * 1/2
= 0.0875 moles of PbCl2
Hence; PbO yields the least number of moles of product so it is the limiting reactant and HCl is the reactant in excess
Answer:
Final temperature =
Explanation:
Given that,
Heat added, Q = 250 J
Mass, m = 30 g
Initial temperature, T₁ = 22°C
The Specific heat of Cu= 0.387 J/g °C
We know that, heat added due to the change in temperature is given by :
Put all the values,
So, the final temperature is equal to .