Answer:
ΔH rx = -43.5 kJ / mol
Explanation:
In water, Xdissolves thus:
X(s) + H₂O(l) → X(aq) + H₂O(aq)
It is possible to find the heat in dissolution process using coffee cup calorimeter equation:
Q = -m×C×ΔT
<em>Where Q is heat, m is mass of solution (35.0g -density 1g/mL- + 2.20g = 37.2g), C is specific heat of solution (4.18J/g°C), and ΔT is change in temperature (26.0°C-15.0°C = 11.0°C)</em>
Replacing:
Q = -37.2g×4.18J/g°C×11.0°C
Q = -1710J = -<em>1.71kJ</em>
As enthalpy is the change in heat per mole of reaction, moles of X that reacted were:
2.20g X × (1mol / 56.0g) = <em>0.0393 moles</em>
As heat produced per 0.0393moles was -1.71kJ, heat per mole of X is:
-1.71kJ / 0.0393mol = -<em>43.5 kJ / mol = ΔH rx</em>
The amine here is the easiest to spot since there’s only one structure that has a nitrogen atom, which would be the first (the first structure is a primary amine).
The distinguishing functional group of an alcohol is the hydroxy group (—OH). Both the second and third structures have an —OH group, but the —OH in the third structure is part of a carboxyl group (—COOH or —C(=O)OH). A carboxyl group takes priority over hydroxy group. Thus, the second structure would be an alcohol and the third structure would be a carboxylic acid.
That leaves us with the fourth structure, a hydrocarbon with a halogen substitutent, or, aptly named, a halocarbon.
Moles of Helium = 39.1 moles
ΔT = (38.08 – 0.08) ֯C = 38.00 ֯C
Q = nC ΔT = 39.1 * 20.8 J/ ֯C mol * 38.00 ֯C = 30904.64 J
W
= P * <span>ΔV = 1atm * (948 - 876) L =
122 atmL</span>
1atmL = 101.325 J
W = 122 * 101.325 J = 12361.65 J
ΔE = q + W = (30904.64 + 12361.65) J = 43266.29 J
Answer is 43266.29 J
