Sam follows the directions on a box of pancake mix. The box says that it makes 10 pancakes, but he is able to make 8 pancakes fr
2 answers:
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Answer:
Explanation:
We are asked to find how much heat a sample of copper absorbs when the temperature is increased.
Since we know the mass, temperature increase, and specific heat capacity, we can use the following formula to calculate heat.
The mass of the copper sample is 100 grams, the temperature is changed or increased by 30.0 degrees Celsius, and the specific heat of copper is 0.39 Joules per gram degrees Celsius.
- m= 100 g
- c= 0.39 J/g °C
- ΔT= 30.0 °C
Substitute the values into the formula.
Multiply the first two values. Note that the units of grams cancel.
Multiply again, this time the units of degrees Celsius cancel.
The copper sample absorbs <u>1170 Joules</u> of heat and <u>Choice B </u>is correct.
Answer:
Explanation:
<u>Convert Atoms to Moles</u>
The first step is to convert atoms to moles. 1 mole of every substance has the same number of particles: 6.022 ×10²³ or Avogadro's Number. The type of particle can be different, in this case it is atoms of silver. Let's create a ratio using this information.
We are trying to find the mass of 8.23 ×10²³ silver atoms, so we multiply by that number.
Flip the ratio so the atoms of silver cancel. The ratio is equivalent, but places the other value with units "atoms Ag" in the denominator.
Condense into one fraction.
<u>Convert Moles to Grams</u>
The next step is to convert the moles to grams. This uses the molar mass, which is equivalent to the atomic mass on the Periodic Table, but the units are grams per mole.
- Ag: 107.868 g/mol
Let's make another ratio using this information.
Multiply by the number of moles we calculated.
The moles of silver cancel out.
<u>Round</u>
The original measurement of atoms has 3 significant figures, so our answer must have the same. For the number we calculated, that is the ones place.
- 147.<u>4</u>184058
The 4 in the tenths place tells us to leave the 7 in the ones place.
8.23 ×10²³ silver atoms are equal to approximately <u>147 grams.</u>