1. A 4.61 g sample of one of the substances listed in the table below was heated from 21.3°C to 315.7°C, requiring 190 J to do so. What substance was heated?
I got mercury(l)
2. Calculate the energy required in joules and calories to heat 33.9 g of aluminum from 30.7°C to 42.8°C. (shc of aluminum is 0.89 j/g C)
What i got:
cal = 87.253609
joule = 365.0691
For #1 you didn't list the choices.
190 = 4.51 x Z x (315.7-21.3) and solve for Z.
For #2, your numbers are ok but you have too many significant figures.
1. To determine the substance that was heated, we first need to calculate the heat capacity of the sample. The heat capacity (C) can be calculated using the formula:
C = Q / (m * ΔT)
Where:
C is the heat capacity in J/g°C
Q is the energy transfer in Joules (in this case, 190 J)
m is the mass in grams (in this case, 4.61 g)
ΔT is the change in temperature in °C (in this case, 315.7°C - 21.3°C = 294.4°C)
Using the given values, we can calculate the heat capacity:
C = 190 J / (4.61 g * 294.4°C) ≈ 0.026 J/g°C
Now, we refer to a table of specific heat capacities to identify the substance with a heat capacity closest to the calculated value. Based on the given answer, mercury (l) seems to be the substance with a specific heat capacity of approximately 0.03 J/g°C.
2. To calculate the energy required to heat a sample of aluminum, we use the formula:
Q = m * C * ΔT
Where:
Q is the energy transfer in Joules
m is the mass in grams (in this case, 33.9 g)
C is the specific heat capacity in J/g°C (in this case, 0.89 J/g°C)
ΔT is the change in temperature in °C (in this case, 42.8°C - 30.7°C = 12.1°C)
Using the given values, we can calculate the energy required:
Q = 33.9 g * 0.89 J/g°C * 12.1°C ≈ 365.07 Joules
To convert the answer to calories, we know that 1 calorie is equal to approximately 4.184 Joules. Therefore, we can calculate the energy required in calories:
365.07 J * (1 cal / 4.184 J) ≈ 87.25 calories (rounded to two decimal places)
So, the energy required to heat 33.9 g of aluminum from 30.7°C to 42.8°C is approximately 365.07 Joules and 87.25 calories.