Answer:
a) 65.74 ± 0.01
b) 60.009 ± 0.001
c) 66 ± 1
d) 65.750 ± 0.001
Explanation:
When reporting results, scientist usually specify a range of values that they expect this "true value" to fall within. The most common way to show this range of values is: measurement = best estimate ± uncertainty
Uncertainties are almost always quoted to one significant digit (example: ±0.05 s).
Wrong: 34.3 cm ± 4.3 cm
Correct: 34 cm ± 4 cm
Always round the experimental measurement or result to the same decimal place as the uncertainty.
Wrong: 1.237 s ± 0.1 s
Correct: 1.2 s ± 0.1 s
Therefore for to answer the question:
a) 65.74 ± 0.01
b) 60.009 ± 0.001
c) 66 ± 1
d) 65.750 ± 0.001
I hope you find this information useful and interesting! Good luck!
Answer:Water absorbs different wavelengths of light to different degrees. The longest wavelengths, with the lowest energy, are absorbed first. Red is the first to be absorbed, followed by orange & yellow. The colors disappear underwater in the same order as they appear in the color spectrum. Even water at 5ft depth will have a noticeable loss of red. For this reason, strobes are usually used to add color back to subjects.
Explanation:
Molarity of solution is defined as number of moles present in one liter solution. Mathematically, it is expressed as
Molarity =
Thus, if 1 mole of solute is present in 1 liter solution, molarity of solution is 1 M.
In present case, initial conc, of solution was 1.25 M.
∴ Number of moles of <span>co[h2o]6cl2 available initially = 1.25 mole, if the solution is 1 liter</span>
The Relative Formula Mass of NaH2PO4 is 120 g/mol
Therefore, the number of moles = 6.6/120
= 0.055 moles of NaH2PO4 which is also equal to the number of moles of H2PO4.
[H2PO4-] = Number of moles oof H2PO4-/Volume of the solution in L
= 0.055/ ( 355 ×10^-3)
= 0.155 M
Na2HPO4 undergoes complete dissociation as follows;
Na2HPO4 (aq)= 2Na+ (aq) + HPO4^2- (aq)
1 mole of Na2HPO4 = 142 g/mol
Therefore; number of moles = 8.0/142
= 0.0563 moles
[HPO4 ^-2] is given by no of moles HPO4^2- /volume of the solution in L
= 0.0563/(355×10^-3)
= 0.1586 M
Both H2PO4^2- and HPO4^2- are weak acids the undergoes partial dissociation
Ka of H2PO4- = 6.20 × 10^-8
[H+] =Ka*([H2PO4-]/[HPO4(2-)]
= (6.20 ×10^-8)×(0.155/0.1586)
= 6.059 ×10^-8 M
pH = - log[H+]
= - log (6.059×10^-8)
= 7.218
