Question

calculate the amount of heat in kj necessary to raise the temperature of 135.0 g of water from 50.4°f to 85.0°f. the specific heat of water = 4.184 j/g·°c. your answer should have 3 significant figures) add your answer integer, decimal, or e notation allowed 2 points question 5 which of the following has a δh°f = 0 kj/mol? a n₂(g) b no(g) c fe²⁺(aq) d h₂o(l)

Explanation:

Step1: Convert Fahrenheit to Celsius

The formula to convert Fahrenheit to Celsius is \(T_{C}=\frac{5}{9}(T_{F} - 32)\).
For \(T_{1}=50.4^{\circ}F\), \(T_{C1}=\frac{5}{9}(50.4 - 32)=\frac{5}{9}\times18.4 = 10.22^{\circ}C\)
For \(T_{2}=85.0^{\circ}F\), \(T_{C2}=\frac{5}{9}(85.0 - 32)=\frac{5}{9}\times53 = 29.44^{\circ}C\)
The change in temperature \(\Delta T=T_{C2}-T_{C1}=29.44 - 10.22=19.22^{\circ}C\)

Step2: Calculate the heat

The formula for heat is \(q = mc\Delta T\), where \(m = 135.0g\), \(c=4.184J/g\cdot^{\circ}C\), \(\Delta T = 19.22^{\circ}C\)
\(q=135.0\times4.184\times19.22\)
\(q = 135.0\times4.184\times19.22=135.0\times80.48648 = 10865.6748J\)

Step3: Convert joules to kilojoules

Since \(1kJ = 1000J\), \(q=\frac{10865.6748}{1000}=10.8656748kJ\approx10.9kJ\) (rounded to 3 significant figures)

Answer:

\(10.9\)