<span>(1) For multiplication and division, you determine the number of significant digits in each number in your problem. The significant digits of your answer is determined by the number with fewer digits. (2) For addition and subtraction, you determine the place value of each number in your problem. The significant digits of the answer is determined by the number that is least precise.</span>
Answer:
ΔH = -976.5 kJ
Explanation:
For the reaction given, there are 2 moles of benzene (C6H6). The heat of this reaction is -6278 kJ, which means that the combustion of 2 moles of benzene will lose 6278 kJ of heat. It is an exothermic reaction.
The value of ΔH, the enthalpy, is a way of measurement of the heat, and it depends on the quantity of the matter (number of moles).
So, 24.3 g of benzene has :
n = mass/ molar mass
n = 24.3/78.11
n = 0.311 moles
2 moles ------------ -6278 kJ
0.311 moles ----------- x
By a simple direct three rule:
2x = -1953.08
x = -976.5 kJ
<span>Hydrated copper sulphate means containing water.
</span><span> Anhydrous copper sulphate means water was removed.
Answer: </span><span>a. LOSS OF WATER.</span>
