The heat used in phase changes is calculated by multiplying the mass of the substance by the energy of the phase change. In this case, for liquid to boil, we would find total heat by multiply the mass of liquid by the latent heat of vaporization (Hvap). If we are instead given the Hvap and the total heat of 1 kJ, we would divide 1 kJ by the Hvap (which is usually in kJ/kg) to get the mass of liquid boiled (in kg).
Answer:
Explanation:
We are given the mass, specific heat, and temperature, so we must use this formula for heat energy.
The mass is 5 grams, the specific heat capacity is 0.14 Joules per gram degree Celsius. Let's find the change in temperature.
- ΔT= final temperature - initial temperature
- ΔT= 95°C - 15°C = 80°C
We know the variables and can substitute them into the formula.
Multiply the first numbers. The grams will cancel.
Multiply again. This time the degrees Celsius cancel.
56 Joules of heat are needed.
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Answer:</h3>
1.001
120.0
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Explanation:</h3>
Significant figures are used in science to determine the precision of a number. Depending on the decimal point, sig figs are counted in different ways.
Decimal Points
When counting sig figs, you always start at the first non-zero number. However, sometimes you start from the left, other times the right.
- If the decimal point is present, start counting sig figs from the left.
- If the decimal point is absent, start counting sig figs from the right.
Remember to start counting at the first non-zero number.
For people in the Americas, there is a trick to remembering this.
- If this decimal is Present, start from the Pacific. If it is Absent, start from the Atlantic.
This works because the Pacific ocean is to the left of the Americas, and the Atlantic is to the right.
4 Significant Figures
The number 1.001, has 4 significant figures. Since there is a decimal point, we start counting from the left. The first digit is not zero, so we count all four places as significant.
The number 120.0 also has 4 sig figs. Like the number above, we start counting from the left because of the decimal. The first digit on the left is not zero, so we once again count all 4 digits as significant.
Answer:
The answer to your question is:
Explanation:
1 mol = 6.022 x 10 ²³ atoms
755 moles = x
x = 755 x 6.022 x 10 ²³ / 1 = 4.54 x 10 ²⁶ atoms
