The calorimeter pictured below shows the final temperature after calcium chloride was added to water. (The initial temperature w
2 answers:
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Answer:
Explanation:
We are asked to find how many moles are in 4.8 × 10²³ fluorine atoms. We convert atoms to moles using Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are atoms of fluorine.
We will convert using dimensional analysis and set up a ratio using Avogadro's Number.
We are converting 4.8 × 10²³ fluorine atoms to moles, so we multiply the ratio by this number.
Flip the ratio so the units of atoms of fluorine cancel each other out.
Condense into 1 fraction.
Divide.
The original measurement of atoms has 2 significant figures, so our answer must have the same. For the number we found, that is the hundredths place. The 7 in the thousandths tells us to round the 9 in the hundredths place up to a 0. Then, we also have to round the 7 in the tenths place up to an 8.
4.8 × 10²³ fluorine atoms are equal to <u>0.80 moles of fluorine.</u>
Answer: The amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours
Explanation:
We are given:
Moles of electron = 1 mole
According to mole concept:
1 mole of an atom contains number of particles.
We know that:
Charge on 1 electron =
Charge on 1 mole of electrons =
is passed to deposit = 1 mole of copper
63.5 g of copper is deposited by = 193000 C
of copper is deposited by =
To calculate the time required, we use the equation:
where,
I = current passed = 40.0 A
q = total charge = 42551181 C
t = time required = ?
Putting values in above equation, we get:
Converting this into hours, we use the conversion factor:
1 hr = 3600 seconds
So,
Hence, the amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours