Ethanol (C2H5OH) boils at a temperature of 78.3oC.
What amount of energy, in joules, is necessary to heat to boiling and then completely vaporize a 20.0 g sample of ethanol initially at a temperature of 13.6oC.
The specific heat of ethanol is approximately constant at 2.44 JK-1g-1
The heat of vaporization of ethanol is 38.56 kJ mol-1.
energy= mass*Lf+ mass*c*deltaTemp
look at the units of the constants.
Hv is in kJ per mole.
energy= moles*Lf+mass*c*deltaTEmp
now, for the first term, convert 20g ethanol to moles ethanol, and you have it.
a player uses a hockey stick to increase the speed of a 0.200kg hockey puck by 6 m/s in 2 seconds how much did the hockey puck accelerate
To calculate the amount of energy required to heat and vaporize ethanol, we need to consider two separate processes: heating the ethanol to its boiling point and then vaporizing it.
Step 1: Calculate the amount of energy required to heat the ethanol to its boiling point.
The specific heat formula is given by:
q = m * c * ΔT
where:
q is the amount of heat energy
m is the mass of the substance (in grams)
c is the specific heat capacity of the substance (in J/(g·K))
ΔT is the change in temperature (in K)
Given:
m = 20.0 g
c = 2.44 J/(g·K)
ΔT = (78.3 - 13.6) = 64.7°C = 64.7 K
Using the specific heat formula, we can calculate the amount of energy required to heat the ethanol:
q1 = m * c * ΔT
q1 = 20.0 g * 2.44 J/(g·K) * 64.7 K
Step 2: Calculate the amount of energy required to vaporize the ethanol.
The heat of vaporization formula is given by:
q = ΔHvap * n
where:
q is the amount of heat energy
ΔHvap is the heat of vaporization (in J/mol)
n is the number of moles
To find the number of moles, we need to use the molar mass of ethanol (C2H5OH):
C: 12.01 g/mol
H: 1.01 g/mol
O: 16.00 g/mol
Adding them up: 2*C + 6*H + O = 2*12.01 + 6*1.01 + 16.00 = 46.07 g/mol
Using the molar mass, we can calculate the number of moles:
n = m / M
n = 20.0 g / 46.07 g/mol
Now we can calculate the amount of energy required to vaporize the ethanol:
q2 = ΔHvap * n
q2 = 38.56 kJ/mol * (20.0 g / 46.07 g/mol) * 1000 J/kJ
Finally, we can add the two energy values together to get the total energy required:
Total energy = q1 + q2
To get the final answer, you will need to calculate q1, q2, and add them together.
To calculate the amount of energy required to heat and vaporize the ethanol, we need to break down the process into two steps: heating the ethanol to its boiling point and then vaporizing it. Let's start with the first step.
Step 1: Heating the ethanol to its boiling point.
To calculate the heat energy required to raise the temperature of a substance, we use the formula:
q1 = msΔT
Where:
q1 = heat energy
m = mass of the substance (20.0 g)
s = specific heat capacity of the substance (2.44 J g^(-1) K^(-1))
ΔT = change in temperature (final temperature - initial temperature)
Substituting the values into the formula:
q1 = (20.0 g) x (2.44 J g^(-1) K^(-1)) x (78.3 °C - 13.6 °C)
Make sure to convert the temperature to Kelvin by adding 273.15.
q1 = (20.0 g) x (2.44 J g^(-1) K^(-1)) x (351.45 K - 286.75 K)
Now calculate the value of q1.
q1 = 20.0 g x 2.44 J g^(-1) K^(-1) x 64.7 K
Step 2: Vaporizing the ethanol.
To calculate the heat energy required to vaporize a substance, we use the formula:
q2 = nΔH
Where:
q2 = heat energy
n = number of moles of the substance
ΔH = enthalpy of vaporization
To find the number of moles of ethanol, we need to know the molar mass. The molar mass of ethanol is approximately 46.07 g/mol (2 x 12.01 g/mol for carbon, 6 x 1.01 g/mol for hydrogen, and 16.00 g/mol for oxygen).
Number of moles of ethanol = mass / molar mass
Number of moles of ethanol = 20.0 g / 46.07 g/mol
Substitute the values into the formula:
q2 = (20.0 g / 46.07 g/mol) x (38.56 kJ/mol)
Now convert the kilojoules to joules and calculate the value of q2.
q2 = (20.0 g / 46.07 g/mol) x (38.56 kJ/mol) x (1000 J/1 kJ)
Finally, add the two steps together to get the total energy required:
Total energy = q1 + q2
By solving these equations, you should be able to find the amount of energy required to heat and vaporize the ethanol sample.