Based on Beer-Lambert's Law,
A = εcl ------(1)
where A = absorbance
ε = molar absorptivity
c = concentration
l = path length
Step 1: Calculate the concentration of the diluted Fe3+ standard
Use:
V1M1 = V2M2
M2 = V1M1/V2 = 10 ml*6.35*10⁻⁴M/55 ml = 1.154*10⁻⁴ M
Step 2 : Calculate the concentration of the sample solution
Based on equation (1) we have:
A(Fe3+) = ε(1.154*10⁻⁴)(1)
A(sample) = ε(C)(4.4)
It is given that the absorbances match under the given path length conditions, i.e.
ε(1.154*10⁻⁴)(1) = ε(C)(4.4)
C = 0.262*10⁻⁴ M
This is the concentration of Fe3+ in 100 ml of well water sample
Step 3: Calculate the concentration of Fe3+ in the original sample
Use V1M1 = V2M2
M1 = V2M2/V1 = 100 ml * 0.262*10⁻⁴ M/35 ml = 7.49*10⁻⁵M
Ans: Concentration of F3+ in the well water sample is 7.49*10⁻⁵M
It was a compound, hence it needed to be separated into its individual components by chemical means.
Answer:
D
Explanation:
When molecules absorb energy they speed up and have a more forceful collision with solute molecules.
Answer:
There are 8.55ₓ10²⁵ atoms of P, in 7.1 moles of Cu₃(PO₄)₂
Explanation:
Copper (II) ⇒ Cu²⁺
PO₄⁻³ → phosphate
3Cu²⁺ + 2PO₄⁻³ → Cu₃(PO₄)₂
1 mol of copper (II) phosphate has 2 mol of P, 8 moles of O and 3 moles of Cu.
Then, 7.10 moles of salt has (7.1 .2) = 14.2 moles of P
In 1 mol we find, NA atoms (6.02ₓ10²³)
In 14.2 moles we would find (14.2 .NA) = 8.55ₓ10²⁵ atoms
Chemical reaction: 2Mg + O₂ → 2MgO. ΔH = -1204 kJ.
ΔH(reaction) = -233 kJ.
From chemical reaction we can se that two moles of magnesium oxide produce -1204 kJ, make proportion:
2 mol : -1204 kJ = n(MgO) : -233 kJ.
n(MgO) = 0,387 mol.
m(MgO) = n(MgO) · M(MgO).
m(MgO) = 0,387 mol · 40,3 g/mol.
m(MgO) = 15,596 g.
