The heat is measured with degree Celsius and degree Fahrenheit. The heat capacity depends on both it's mass and it's chemical composition.
In this redox reaction, the Cu goes from oxidation state of (0) to (+2), therefore it oxidises. N in HNO₃ goes from oxidation state of (+5) to N in NO with oxidation state of (+2) and becomes reduced.
Cu acts as the reducing reagent and HNO₃ is the oxidising agent.
oxidation half reaction
Cu ---> Cu²⁺ + 2e --1)
reduction half reaction
4H⁺ + 3e + NO₃⁻ ---> NO + 2H₂O --2)
to balance the number of electrons , 1) x3 and 2) x2
3Cu ---> 3Cu²⁺ + 6e
8H⁺ + 6e + 2NO₃⁻ ---> 2NO + 4H₂O
add the 2 equations
3Cu + 8H⁺ + 2NO₃⁻ ---> 3Cu²⁺ + 2NO + 4H₂O
add 6 nitrate ions to both sides to add up to 8 and form acid with 8H⁺ ions
3Cu + 8HNO₃ ---> 3Cu(NO₃)₂ + 2NO + 4H₂O
Balanced equation for the redox reaction is as follows;
3Cu(s) + 8HNO₃(aq) → 3Cu(NO₃)₂(aq) + 2NO(g) + 4H₂O<span>(l)
NO has a coefficient of 2
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Solution;
The gas is at STP;
Where; T = 273 K , P = 1 atm
We know that 1 mole of a gas at STP occupies a volume of 22.4 liters .
V1/n1 = V2/n2
n2 = (V2/V1) n1
n2 = (2 l/22.4 l)(1 mole)
n2 = 0.0893 moles
But 1 mole of a compound has 6.022 × 10^23 molecules
Thus, number of molecules = 0.0893 moles × 6.022 ×10^23 molecules
= 5.378 × 10^22 molecules.
