Answer:
The mass percent of sulfur is 9.98%.
Explanation:
<em>The percentage of sulfur in coal can be determined by burning a sample of the solid and passing the resulting sulfur dioxide gas into a solution of hydrogen peroxide, which oxidizes it to sulfuric acid, and then titrating the acid.</em>
The corresponding balanced equations are:
S + O₂ ⇄ SO₂ [1]
SO₂ + H₂O₂ ⇄ H₂SO₄ [2]
H₂SO₄ + 2 NaOH ⇄ Na₂SO₄ + 2 H₂O [3]
First, we have to calculate how many moles of NaOH we have.
n = 0.114 mol/L × 0.441 L = 0.0502 mol
Then, we will use the following relations:
- According to [3], 2 moles of NaOH react with 1 mole of H₂SO₄
- According to [2], 1 mole of H₂SO₄ is produced per mole of SO₂
- According to [1], 1 mole of SO₂ is produced per mole of S
- The molar mass of S is 32.0 g/mol
Then, for 0.0502 moles of NaOH:
If there are 0.803 g of S in an 8.05 g sample, the mass percent of sulfur is:
Answer:
Explanation:
Use the trigonometric ratio definition of the tangent function and the quotient rule.
Quotient rule: the derivative of a quotient is:
- [the denominator × the derivative of the numerator less the numerator × the derivative of the denominator] / [denominator]²
- (f/g)' = [ g×f' - f×g'] / g²
So,
- tan(x)' = [ sin(x) / cos(x)]'
- [ sin(x) / cos(x)]' = [ cos(x) sin(x)' - sin(x) cos(x)' ] / [cos(x)]²
= [ cos(x)cos(x) + sin(x) sin(x) ] / [ cos(x)]²
= [ cos²(x) + sin²(x) ] / cos²(x)
= 1 / cos² (x)
= sec² (x)
The result is that the derivative of tan(x) is sec² (x)
2/3 moles thats the answer