Answer:
0.08 mL
Explanation:
The solution of the skin test has a concentration of 0.2% (w/v), which means that there are 0.2 g of the antigen per 100 mL of the solution. If a new solution will be done using it, then this solution will be diluted, and the mass of the antigen added must be the same in the volume taken and at the diluted solution.
The mass is the concentration (in g/mL) multiplied by the volume of the solution (in mL), so, if m is the mass, C the concentration, V the volume, 1 the initial solution, and 2 the diluted:
m1 = m2
C1*V1 = C2*V2
Where
C1 = 0.2 g/100 mL = 0.002 g/mL
V1 = ?
C2 = 0.04 mg/mL = 0.00004 g/mL
V2 = 4 mL
0.002*V1 = 0.00004*4
V1 = 0.08 mL
Answer:
76.1%
Explanation:
The reaction that takes place is:
- BaCl₂ + K₂SO₄ → BaSO₄ + 2KCl
First we determine how many moles of each reactant were added:
- BaCl₂ ⇒ 80 mL * 0.812 M = 64.96 mmol BaCl₂
- K₂SO₄ ⇒ 40 mL * 1.52 M = 60.8 mmol K₂SO₄
Thus K₂SO₄ is the limiting reactant.
Using the <em>moles of the limiting reactant</em> we <u>calculate how many moles of BaSO₄ would have been produced if the % yield was 100%</u>:
- 60.8 mmol K₂SO₄ *
= 60.8 mmol BaSO₄
Then we <u>convert that theoretical amount into grams</u>, using the <em>molar mass of BaSO₄</em>:
- 60.8 mmol BaSO₄ * 233.38 mg/mmol = 14189.504 mg BaSO₄
- 14189.504 mg BaSO₄ / 1000 = 14.2 g BaSO₄
Finally we calculate the % yield:
- % yield = 10.8 g / 14.2 g * 100 %
Answer:
50g
Explanation:
Please see the step-by-step solution in the picture attached below.
Hope this answer can help you. Have a nice day!