Answer: mass = 19 grams
Explanation: Density is directly proportional to mass and indirectly proportional to the volume. So, the density formula is:
density and volume are given and the question asks to calculate the mass. So, the formula could be rearranged as:
mass = density x volume
Given density is and the volume is
.
Let's plug in the values in the formula to calculate the mass:
mass =
mass = 19.24 grams
Both the density and volume have two sig figs, so if the answer is round off to correct number of sig figs then the mass will be 19 grams.
Answer:
1.48×10²⁴ Cu atoms
Explanation:
For this question you need to use Avogadro's number 6.022×10²³atoms.
2.45 moles of Cu ×= 1.47539×10²⁴ atoms.
The moles cancel out so you are left with atoms.
Since there are 3 significant figures in the question there should be 3 significant figures in your answer, which is 1.48×10²⁴ Cu atoms.