IF 8.5g of KOH powder are placed in 100g of water at room temperature of 20degree Celsius, what is the final temperature of the solution.
KOH K+OH H=-57.61 KJ/MOL KOH
if the heat of solution is -57.62kj per mole, the question is what portion of a mole is 8.5 grams?
8.5/56.1=...
Now the sum of heats gained is zero.
8.5/56.1*57.64+100g* 4.18kj/kg*(tf-20)=0
tf-20= 8.7/.418
solve for temp final tf. Check my work
when calculating the heat gained by solution, the total mass will be 108.5 gm not 100gm. Since there was 8.5g of KOH added to water.
Well, I guess you could say that the KOH powder really knows how to heat things up! But let's put the laughter aside for a moment and tackle this chemistry problem.
To solve this, we can use the formula Q = m * c * ΔT, where Q is the heat transfer, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature.
First, we need to find the heat transfer (Q) when the KOH powder dissolves in the water. Using the given enthalpy change of -57.61 kJ/mol KOH, we can calculate the heat transfer as follows:
Q = (-57.61 kJ/mol KOH) * (8.5 g / 56.11 g/mol KOH)
= -8.73 kJ
Next, we'll find the specific heat capacity of water, which is approximately 4.18 J/g°C.
Now, let's plug the values into the formula. Assuming no heat loss to the surroundings, we can set the heat transfer equal to zero since the final temperature of the solution is not given. This will allow us to solve for the change in temperature (ΔT) using the formula:
0 = (100 g + 8.5 g) * 4.18 J/g°C * ΔT
Solving for ΔT, we get:
ΔT = 0 J / (108.5 g * 4.18 J/g°C)
≈ 0 °C
So, it seems that the final temperature of your solution would remain around the initial temperature of 20°C, assuming no heat loss. But hey, at least the KOH powder didn't make things steamy!
To find the final temperature of the solution, we can use the concept of heat transfer.
First, let's calculate the amount of heat released when 8.5g of KOH powder is dissolved in water. We can use the molar mass of KOH to find the number of moles:
Molar mass of KOH = (39.1 g/mol for K) + (16.0 g/mol for O) + (1.0 g/mol for H) = 56.1 g/mol
Number of moles of KOH = mass of KOH / molar mass of KOH
= 8.5 g / 56.1 g/mol
Next, let's calculate the heat released when the KOH dissolves:
Heat released = number of moles of KOH * heat of solution per mole of KOH
= (8.5 g / 56.1 g/mol) * -57.61 kJ/mol
Now, we can use the heat released to determine the temperature change of the solution:
Heat released = mass of water * specific heat capacity of water * temperature change
Assuming the specific heat capacity of water is 4.18 J/g°C, we can rearrange the equation and solve for the temperature change:
Temperature change = heat released / (mass of water * specific heat capacity of water)
= (heat released * 1000) / (100 g * 4.18 J/g°C)
Finally, we can calculate the final temperature of the solution by adding the temperature change to the initial temperature of 20°C:
Final temperature of the solution = Initial temperature + Temperature change
Therefore, the final temperature of the solution is:
Final temperature = 20°C + Temperature change
To determine the final temperature of the solution, we can use the concept of heat transfer. The heat gained or lost by the water can be calculated using the formula:
q = m * C * ΔT
Where:
q is the heat gained or lost (in Joules)
m is the mass of the water (in grams)
C is the specific heat capacity of water (4.18 J/g°C)
ΔT is the change in temperature (final temperature - initial temperature)
In this case, the heat lost by the KOH powder when it dissolves in the water will be equal to the heat gained by the water. We can calculate the heat lost by the KOH using the following equation:
q = -ΔH
Where:
q is the heat lost by the KOH (in Joules)
ΔH is the enthalpy change (in this case, -57.61 kJ/mol KOH)
First, we need to calculate the number of moles of KOH in the solution using the given mass and molar mass of KOH (39.1 g/mol + 16.0 g/mol + 1.0 g/mol = 56.1 g/mol):
n = m / M
Where:
n is the number of moles of KOH
m is the mass of KOH (8.5 g)
M is the molar mass of KOH (56.1 g/mol)
n = 8.5 g / 56.1 g/mol = 0.151 mol KOH
Next, we can calculate the heat lost by the KOH:
q = -ΔH = -57.61 kJ/mol KOH * 0.151 mol KOH = -8.70311 kJ
Since 1 kJ = 1000 J, we need to convert the heat value to Joules:
q = -8.70311 kJ * 1000 J/kJ = -8703.11 J
Now, we can rearrange the first equation to solve for ΔT:
ΔT = q / (m * C)
ΔT = -8703.11 J / (100 g * 4.18 J/g°C) = -20.83 °C
Finally, we can calculate the final temperature of the solution by subtracting the calculated ΔT from the initial temperature:
Final temperature = Initial temperature - ΔT = 20°C - 20.83°C = -0.83°C
Therefore, the final temperature of the solution is approximately -0.83°C.