The reaction produces 2.93 g H₂.
M_r: 133.34 2.016
2Al + 6HCl → 2AlCl₃ + 3H₂
<em>Moles of AlCl₃</em> = 129 g AlCl₃ × (1 mol AlCl₃/133.34 g AlCl₃) = 0.9675 mol AlCl₃
<em>Moles of H₂</em> = 0.9675 mol AlCl₃ × (3 mol H₂/2 mol AlCl₃) = 1.451 mol H₂
<em>Mass of H₂</em> = 1.451 mol H₂ × (2.016 g H₂/1 mol H₂) = 2.93 g H₂
You multiply the number of atoms by 12 to get how many electrons (since each atom has 12 electrons in it)
you multiply the number of atoms by 13 to get how many neutrons
(since each atom of this isotope has 13 neutrons in it)
Answer: There are five significant figures in 865,010.
Explanation:
When a degree of accuracy is stated by each digit present in a mathematical figure then it is called a significant figure.
Rules for counting significant figures is as follows.
- Any non-zero digits and zeros present between a non-zero figure are counted. For example, 3580009 has seven significant figures.
- Trailing zeros are counted in a non-zero figure. For example, 0.00250 has three significant figures.
- Leading zeros are not counted. For example, 0.0025 has two significant figures.
So, in the given figure 865010 has five significant figures and the trailing zero will not be counted.
Thus, we can conclude that there are five significant figures in 865,010.
