Answer: 0.34 mol
Justification:
1) Hepta means 7, so heptahyrate means 7 parts of water. On mole of magnesium sulfate heptadydrate has seven moles of water.
2) The formula of magnesium sulfate heptahydrate is:
Mg SO4 . 7 H2O
3) Calcualte the number of moles of the compound by dividing the mass in grams by the molar mass of formula.
molar mass:
Mg: 24.3 g/mol
S: 32.1 g/mol
O4: 4 * 16.0 g/mol = 64.0 g/mol
H2: 2 * 1.0 g/mol = 2.0 g/mol
O: 16 g/mol
Molar mass = 24.3 g/mol + 32.1 g/mol + 64.0 g/mol + 2.0 g/mol + 16.0 g/mol = 138.4 g/mol
number of moles = mass in grams / molar mass = 6.81 g / 138.4 g/mol = 0.049 mol
4) As stated, there are 7 moles of H2O per each mol of heptahydrate compoind, so the number of moles of water is 7 * 0.049 mol = 0.343 mol
Answer: 0.34 mol
The change in pH is calculated by:
pOH = Protein kinase B + log [NH4+]/ [NH3]
Protein kinase B of ammonia = 4.74
initial potential of oxygen hydroxide= 4.74 + log 0.100/0.100 = 4.74
pH = 14 - 4.74=9.26
moles NH4+ = moles NH3 = 0.100 L x 0.100 M = 0.0100
moles H+ added = 3.00 x 10^-3 L x 0.100 M=0.000300
NH3 + H+ = NH4+
moles NH3 = 0.0100 - 0.000300=0.00970
moles NH4+ = 0.0100 + 0.000300=0.0103
pOH = 4.74 + log 0.0103/ 0.00970= 4.77
oH = 14 - 4.77 = 9.23
the change is = 9.26 - 9.23 =0.03
If the absorbance of a solution of curcumin which is too concentrated is measured, the absorbance will be unusually high.
Spectrometry measures the interaction of light with molecules. The absorbance refers to how much light that interacts with molecules of the substance. The more the concentration of the substance the higher the absorbance of the solution.
Hence, if the absorbance of a solution of curcumin which is too concentrated is measured, the absorbance will be unusually high. An unusually high absorbance tells us that the solution is too concentrated.
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