For the desired pH of 5.76, 0.365 mol of acetate and 0.035 mol of acid are to be added
let the concentration of acetate be x
then the concentration of acid will be (0.8 - x)
pKa of acetate buffer = 4.76
pH = pKa + log([acetate]/[acid])
⇒4.76 = 4.76 + log(x/(0.8-x))
⇒log(x/(0.8-x)) = 0
⇒x/(0.8-x) = 1
⇒x = 0.4
Therefore
[acetate] = x = 0.4
[acid] = 0.8-x =0.4 M
number of mol = concentration *(volume in mL)
number of mol of acetate = 0.4*0.5
= 0.20 mol
number of mol acid = 0.4*0.5
= 0.20 mol
when desired pH = 5.76
pH = pKa + log([acetate]/[acid])
⇒5.76 = 4.76 + log(x/(0.8-x))
⇒log(x/(0.8-x)) = 1
⇒x/(0.8-x) = 10
⇒x = 8 - 10x
⇒x = 8/11
⇒x= 0.73
[acetate] = x= 0.73
[acid] = 0.8-x = 0.07 M
number of mol = concentration * (volume in mL)
number of mol acetate to be added = 0.73*0.5 = 0.365 mol
number of mol acid to be added = 0.07*0.5 = 0.035 mol
Problem based on acetic acid required to maintain a certain pH
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B and c...will lose electron(s) in forming an Ion.
P is an Anion
b..Fe. and c...Pb form Cations (+) by losing electrons.
d. Se is an Anion.
A stock solution is a solution of a known concentration. Stock solution has a high concentration and therefore, the known amount of stock solution is used for preparing different concentrations, by diluting the same with the known amount of the solvent being used, such as water.
A-leads to the abrasion of rocks and minerals
A-dense vegetation cover
True
Explanation:
Weathering is the physical disintegration and chemical decomposition of rocks to form sediments and soils.
Agent of weathering are wind, water and glacier.
Chemical weathering contributes to physical weathering in that it leads to the abrasion of rocks and minerals.
During chemical weathering, a rock chemically combines with materials in the environment and weakens it.
When physical weathering processes are induced, grains produced independently weakening of bonds in rocks grind against one another and wears each other off.
An area with a dense vegetation cover undergoes rapid chemical weathering:
- Plant roots penetrates deep into the rock and increases the surface area of chemical action.
- Plants produce chemicals that combines with rocks and causes them to decay.
- Since the area is always moist, chemical action becomes more severe.
Buildings and statues made of stone are subjected to the same degree of weathering as rocks exposed naturally.
This is true.
Statues and buildings weather just like rocks we find in nature.
It is the same sunshine and rain that impacts rocks that also impacts buildings and statues.
So they degrade at the same rate except they are protected.
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