Shown below is a balance. Based on this instrument, identify from the following list all the statements that are true if you wer
e to use
this balance to measure the mass of a sample. (Note, the balance in the picture currently reads "0.00")
Choose one or more:
A. a mass measured on this balance will always have 3 significant digits.
B. the uncertainty is in the hundredth place.
C. the uncertainty is in the ones place.
D. a mass measured on this balance will always have 4 significant digits.
E. the uncertainty is in the tenths place.
F. the mass measured on this balance is known exactly.
G. a mass that falls between 1 gram and 9 grams measured on this balance will always have 3 significant figures.
H. a mass that falls between 10 grams and 80 grams measured on this balance will always have 3 significant figures.
I. a mass that falls between 100 and 200 grams measured on this balance will have 5 significant figures.
this balance to measure the mass of a sample. (Note, the balance in the picture currently reads "0.00")
Choose one or more:
A. a mass measured on this balance will always have 3 significant digits.
B. the uncertainty is in the hundredth place.
C. the uncertainty is in the ones place.
D. a mass measured on this balance will always have 4 significant digits.
E. the uncertainty is in the tenths place.
F. the mass measured on this balance is known exactly.
G. a mass that falls between 1 gram and 9 grams measured on this balance will always have 3 significant figures.
H. a mass that falls between 10 grams and 80 grams measured on this balance will always have 3 significant figures.
I. a mass that falls between 100 and 200 grams measured on this balance will have 5 significant figures.
1 answer:
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First we have to find Ka1 and Ka2
pKa1 = - log Ka1 so Ka1 = 0.059
pKa2 = - log Ka2 so Ka2 = 6.46 x 10⁻⁵
Looking at the values of equilibrium constants we can see that the first one is really big compared to second one. so, the pH will be affected mainly by the first ionization of the acid.
Oxalic acid is H₂C₂O₄
H₂C₂O₄ ⇄ H⁺ + HC₂O₄⁻
0.0356 M 0 0
0.0356 - x x x
Ka1 =![\frac{[H^+][HC2O4^-]}{[H2C2O4]}](https://tex.z-dn.net/?f=%20%5Cfrac%7B%5BH%5E%2B%5D%5BHC2O4%5E-%5D%7D%7B%5BH2C2O4%5D%7D%20)
= x² / 0.0356 - x
x = 0.025 M
pH = - log [H⁺] = - log (0.025) = 1.6
pKa1 = - log Ka1 so Ka1 = 0.059
pKa2 = - log Ka2 so Ka2 = 6.46 x 10⁻⁵
Looking at the values of equilibrium constants we can see that the first one is really big compared to second one. so, the pH will be affected mainly by the first ionization of the acid.
Oxalic acid is H₂C₂O₄
H₂C₂O₄ ⇄ H⁺ + HC₂O₄⁻
0.0356 M 0 0
0.0356 - x x x
Ka1 =
x = 0.025 M
pH = - log [H⁺] = - log (0.025) = 1.6