Answer:
108.43 grams KNO₃
Explanation:
To solve this problem we use the formula:
Where
- ΔT is the temperature difference (14.5 K)
- Kf is the cryoscopic constant (1.86 K·m⁻¹)
- b is the molality of the solution (moles KNO₃ per kg of water)
- and<em> i</em> is the van't Hoff factor (2 for KNO₃)
We <u>solve for b</u>:
- 14.5 K = 1.86 K·m⁻¹ * b * 2
Using the given volume of water and its density (aprx. 1 g/mL) we <u>calculate the necessary moles of KNO₃</u>:
- 275 mL water ≅ 275 g water
- moles KNO₃ = molality * kg water = 3.90 * 0.275
- moles KNO₃ = 1.0725 moles KNO₃
Finally we <u>convert KNO₃ moles to grams</u>, using its molecular weight:
- 1.0725 moles KNO₃ * 101.103 g/mol = 108.43 grams KNO₃
Answer:
1. 0.338 moles of Fe
2. 0.700 moles of Fe
3. 48.3%
Explanation:
This is the reaction:
Fe₂O₃ + 3C → 2Fe + 3CO
We were told that we produce 18.9 g of Fe. Let's convert the mass to moles:
18.9 g . 1mol/ 55.85 g = 0.338 moles of Fe
Let's make a rule of three; ratio is 1:2.
1 mol of oxide can produce 2 moles of elemental iron
Then, 0.350 moles must produce (0.350 .2) / 1 = 0.700 moles of Fe
Let's determine the percent yield:
(Yield produced /Theoretical Yield) . 100 = 48.3 %
Explanation:
Using Beer-Lambert's law :
Formula used :
where,
A = absorbance of solution
c = concentration of solution
l = length of the cell
= molar absorptivity of this solution
According to question:
A = (C) : absorbance measured by the spectrometer
c = (B) : concentration, in mol/L, of the stock solution from which the sample was made
l = (A): pathlength of light through the cell
ε = (D) : molar absorptivity, a constant unique to that substance at that wavelength
a. Spectator ions are the ones that are present but does not enter into the actual chemical reaction.
b. Na⁺ and NO₃⁻ ions are spectator ions involved in this above mentioned reaction
<u>Explanation:</u>
- In redox reactions, for example reaction of aqueous silver nitrate and aqueous sodium chloride, silver chloride settles down as a precipitate by the addition of Ag⁺ ion from AgNO₃ and Cl⁻ ions from NaCl .
- The other 2 ions that is NO₃⁻ ion and Na⁺ ion in the reaction do not enter into the reaction and they are called as Spectator ions.
This can be expressed as the following equation,
AgNO₃(aq) + NaCl(aq) →AgCl(s) + NaNO₃
Answer is: 5,9.
Effusion is leakage of gas
through a small hole. Gases with a lower molecular mass effuse more speedy than gases with a higher molecular mass. R<span>elative rates of effusion is related to the molecular mass.
</span>M(O₂) = 32g/mol.
M(CO₂) = 44g/mol.
t₁ = 5s.
t₂ = ?
t₂/t₁ = √(M(CO₂)/M(O₂)).
t₂ = 1,17·5s = 5,9s.
