Multiple Choice
Determine the temperature change that occurs when 10.6 g of potassium perchlorate (KClO4) is dissolved in enough water to make 104.8 mL of solution, given that the enthalpy of dissolution is -55.5 kJ/mol.
1. Intro to General Chemistry
Temperature
Struggling with General Chemistry?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Suppose that to a mug containing 125 mL of water at a temperature of 90.0 °C we add 165 mL of water at an unknown temperature and mix the contents well. What is that unknown temperature if the final temperature of water in the mug is 58.3 °C?
A
25.0 °C
B
60.0 °C
C
45.0 °C
D
30.0 °C
Verified step by step guidance1
Start by understanding the concept of heat transfer. When two bodies of water at different temperatures are mixed, heat will flow from the warmer water to the cooler water until thermal equilibrium is reached.
Use the formula for heat transfer: \( q = m \cdot c \cdot \Delta T \), where \( q \) is the heat exchanged, \( m \) is the mass, \( c \) is the specific heat capacity, and \( \Delta T \) is the change in temperature. For water, \( c \) is approximately \( 4.18 \text{ J/g°C} \).
Calculate the mass of each water sample using the density of water, which is approximately \( 1 \text{ g/mL} \). Therefore, the mass of the first sample is \( 125 \text{ g} \) and the mass of the second sample is \( 165 \text{ g} \).
Set up the equation for heat transfer: \( m_1 \cdot c \cdot (T_{final} - T_1) = m_2 \cdot c \cdot (T_2 - T_{final}) \). Substitute \( m_1 = 125 \text{ g} \), \( T_1 = 90.0 \text{ °C} \), \( m_2 = 165 \text{ g} \), and \( T_{final} = 58.3 \text{ °C} \).
Solve the equation for \( T_2 \), the unknown initial temperature of the second water sample. This involves isolating \( T_2 \) on one side of the equation and performing algebraic manipulations to find its value.
Related Videos
Related Practice
