Answer:
Option (2) 2
Explanation:
NO3- + 4H+ + Pb → Pb2+ + NO2 + 2H2O
The equation above can be balance as follow:
There are 3 atoms of the left side and a total of 4 atoms on the right side. It can be balance by putting 2 in front NO3- and 2 in front of NO2 as shown below:
2NO3- + 4H+ + Pb → Pb2+ + 2NO2 + 2H2O
Now the equation is balanced.
The coefficient of NO2 is 2
Answer:
3000 kJ/kg
Explanation:
The calorific value of a substance is the amount of heat produced per unit mass by the combustion of the substance.
It is given by:
where
Q is the amount of heat released
m is the mass of the fuel
In this problem, we have:
m = 60 kg is the mass of fuel
is the amount of heat released
Therefore, the calorific value of the fuel is:
Answer:
=C₄H₄O₂
Explanation:
Given the empirical formula of a molecule, the he the quotient of the molecular mas and and the empirical mass=constant.
84.0 g/mol/mass of(C₂H₂O)=constant
=84/(12×2+1×2×16)
=84/42
=2
Therefore, the molecular formula is (C₂H₂O)₂=C₄H₄O₂
<span>This question asksyou to apply Hess's law.
You have to look for how to add up all the reaction so that you get the net equation as the combustion for benzene. The net reaction should look something like C6H6(l)+ O2 (g)-->CO2(g) +H2O(l). So, you need to add up the reaction in a way so that you can cancel H2 and C.
multiply 2 H2(g) + O2 (g) --> 2H2O(l) delta H= -572 kJ by 3
multiply C(s) + O2(g) --> CO2(g) delta H= -394 kJ by 12
multiply 6C(s) + 3 H2(g) --> C6H6(l) delta H= +49 kJ by 2 after reversing the equation.
Then,
6 H2(g) + 3O2 (g) --> 6H2O(l) delta H= -1716 kJ
12C(s) + 12O2(g) --> 12CO2(g) delta H= -4728 kJ
2C6H6(l) --> 12 C(s) + 6 H2(g) delta H= - 98 kJ
______________________________________...
2C6H6(l) + 16O2 (g)-->12CO2(g) + 6H2O(l) delta H= - 6542 kJ
I hope this helps and my answer is right.</span>
