Using Hess' Law, we can calculate the heat of reaction of the gasification of coal. Multiplying the second reaction by 2 and reversing the third reaction:
<span>C(s) + O2(g) → CO2(g) ∆H=-394 kj
2H2(s) + O2(g) → H2O(l) ∆H=-572kj
</span>CO2(g) + 2H2O(l) → CH4(g) + 2O2(g) ∆H=891kj
Adding the three reaction would result to
<span>C(s) + 2H2(g) → CH4(g) ∆H = -394 + -572 + 891 = -75 kJ
The answer is
</span><span>(B) -75 kJ
</span>
When the cows eat the grass
Answer:
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the Empirical formula of the compound is calculated as follows
find the moles of each element
moles = mass/molar mass
that is Magnesium= 0.564 g /24 g/mol = 0.0235 moles
For oxygen = 0.376 g /16 g/mol= 0.0235 moles
find the mole ratio by dividing both moles of by 0.0235 moles
magnesium = 0.0235/0.0235= 1mole
oxygen= 0.0235 /0.0235= 1mole
therefore the empirical formula = MgO