How much heat, in kilojoules (kJ), is required to raise the temperature of 2.50kg Hg(l) from -20.0 to -6.0C? Assume a density of 13.6g/ml and a molar heat capacity of 28.0 J mol -1 C -1 for Hg(l).
Please helpppppp .... thanks in advance
*sorry, my conversion of 2.5 kg to g is wrong. The equation should be
Q = (2500 / 200.6)*(28.0)*(-6 -(-20))
Through out the temperature range, Hg remains as liquid.
Recall that heat released or absorbed is given by
Q = m*c*(T2 - T1)
where
m = mass
c = specific heat
T = temperature
Note that molar mass of Hg is 200.6 g/mol.
Substituting,
Q = (250000 / 200.6)*(28.0)*(-6 -(-20))
Q = ?
Now solve for Q. The units are in J, so divide by 1000 to convert to kJ.
Hope this helps :3
Why the density of Hg is given here in above question
-from Pakistan
How much heat is required to raise the temperature of a 2.0 kg of water (specific heat = 1.0 cal/g°C) from 5.0°C to 100.0°C?
Well, well, well, it looks like you've got yourself in a sticky situation! Let's break it down, shall we?
First off, we need to calculate the mass of the mercury. Since density is mass over volume, we can rearrange the equation to solve for mass: mass = density * volume. You know the density of mercury is 13.6 g/ml, and you have 2.50 kg, so the volume can be found as follows:
volume = mass / density = 2500 g / 13.6 g/ml = 183.82 ml
Now, let's convert the volume to liters because we'll need it later. Since 1 L = 1000 ml, we can find the volume in liters by dividing it by 1000:
volume (in liters) = 183.82 ml / 1000 = 0.18382L
Alright, now that we've got that out of the way, let's move on to find the heat energy required. We can use the equation Q = m * C * ΔT, where Q is the heat energy, m is the mass, C is the molar heat capacity, and ΔT is the change in temperature.
Given that the molar heat capacity (C) for mercury is 28.0 J mol^(-1) C^(-1), we need to find the moles of mercury. We can do this using the equation: moles = mass / molar mass. The molar mass of mercury (Hg) is 200.59 g/mol.
moles = mass / molar mass = 2500 g / 200.59 g/mol = 12.45 mol
Finally, let's calculate the heat energy:
Q = m * C * ΔT = moles * C * ΔT = 12.45 mol * 28.0 J mol^(-1) C^(-1) * (–6.0°C – (–20.0°C))
Do the math, and you should get your answer!
Hope that helped lighten the mood a bit! Happy calculations!
To calculate the amount of heat required to raise the temperature of a substance, you can use the formula:
q = m * c * ΔT
Where:
q = heat energy (in joules or J)
m = mass of the substance (in grams or g)
c = specific heat capacity of the substance (in J/g°C or J/gK)
ΔT = change in temperature (in °C or K)
First, let's convert the given mass of mercury (Hg) from kilograms to grams:
2.50 kg * 1000 g/kg = 2500 g
Next, we need to calculate the change in temperature:
ΔT = final temperature - initial temperature
ΔT = -6.0°C - (-20.0°C)
ΔT = 14.0°C
Now, we can substitute the values into the formula and solve for q:
q = 2500 g * 28.0 J/mol°C * 14.0°C
However, we need to convert the mass of mercury from grams to moles. To do this, we will use the molar mass of mercury, which is 200.59 g/mol.
moles of Hg = mass of Hg / molar mass of Hg
moles of Hg = 2500 g / 200.59 g/mol
Substituting this value into the formula, we get:
q = (2500 g / 200.59 g/mol) * 28.0 J/mol°C * 14.0°C
Now, let's calculate:
q ≈ 246,256 J
Finally, if we want the answer in kilojoules, we can convert joules to kilojoules by dividing by 1000:
q ≈ 246.256 kJ
Therefore, approximately 246.256 kilojoules (kJ) of heat is required to raise the temperature of 2.50 kg of Hg(l) from -20.0°C to -6.0°C.