A calorimeter contains 30.0 mL of water at 15.0 C. When 1.50 g of X (a substance with a molar mas of 46.0g/ mol is added, it dissolves via the reaction
X (s) + H2O (l) ----> X (aq)
and the temperature of the solution increases to 26.5 C.
Calculate the enthalpy change for this reaction.
So is the answer supposed to be positive.
No. The temperature increased from 15 to 26.5 and that makes it an exothermic reaction so dH is -.
-14.5
To calculate the enthalpy change for the reaction, you can use the formula:
q = mcΔT
Where:
q is the amount of heat transferred (enthalpy change),
m is the mass of the water in the calorimeter,
c is the specific heat capacity of water, and
ΔT is the change in temperature.
First, let's determine the initial temperature (Ti) of the water:
Ti = 15.0 ˚C
Next, let's determine the final temperature (Tf) of the water:
Tf = 26.5 ˚C
The mass of the water (m) in the calorimeter is given as 30.0 mL. However, since the density of water is 1 g/mL, the mass of the water can be calculated as:
m = 30.0 mL × 1 g/mL = 30.0 g
Now, let's calculate the enthalpy change (q) using the formula:
q = mcΔT
q = (30.0 g) × (4.18 J/g·˚C) × (26.5 ˚C - 15.0 ˚C)
Here, 4.18 J/g·˚C is the specific heat capacity of water.
Solving this, you will get the enthalpy change (q) in joules (J). If the value of q is positive, it means that the reaction is endothermic (absorbs heat), and if it is negative, it means the reaction is exothermic (releases heat).
So, if the enthalpy change (q) is positive, the answer is supposed to be positive.