The correct answer here is C. Dew forms on the grass.
Water is a polar substance, which means it has many unique properties. One of which, is its ability to adhere and cohere to surfaces and substances. This particular question is asking about the cohesive properties of water, meaning it’s ability to stick to itself (through bonding.) The only answer choice that represents a situation where water is linking up with other molecules of water are dew drops. The water comes together using cohesion to form the drop and hen the water’s high surface tension properties meet the dew drop’s shape. The other answer choices describe alternate processes like: freezing, melting, and evaporation, respectively.
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Answer :
The correct answer for primary component of phosphate buffer at pH = 7.4 is H₂PO₄⁻ and HPO₄²⁻ .
<u>Buffer solution :</u>
It is a solution of mixture of weak acid and its conjugate base OR weak base and its conjugate acid . It resist any change in solution when small amount of strong acid or base is added .
<u>Capacity of a good buffer : </u>
A good buffer is identified when pH = pKa .
From Hasselbalch - Henderson equation which is as follows :
![pH = pka + log \frac{[A^-]}{[HA]}](https://tex.z-dn.net/?f=pH%20%3D%20pka%20%2B%20log%20%5Cfrac%7B%5BA%5E-%5D%7D%7B%5BHA%5D%7D)
If [A⁻] = [HA] ,
pH = pka + log 1
pH = pKa
This determines that if concentration of weak acid and its conjugate base are changed in small quantity , the capacity of buffer to maintain a constant pH is greatest at pka . If the amount of [A⁻] or [HA] is changed in large amount , the log value deviates more than +/- 1M and hence pH .
Hence Buffer has best capacity at pH = pka .
<u>Phosphate Buffer : </u>
Phosphate may have three types of acid-base pairs at different pka ( shown in image ).
Since the question is asking the pH = 7.4
At pH = 7.4 , the best phosphate buffer will have pka near to 7.4 .
If image is checked the acid - base pair " H₂PO₄⁻ and HPO₄²⁻ has pka 7.2 which is near to pH = 7.4 .
Hence we can say , the primary chemical component of phosphate buffer at pH = 7.4 is H₂PO₄⁻ and HPO₄²⁻ .
Answer:
Imole/C=129 Directions Show All Of Your Work For Each Of The Following Problems. 1.
Explanation:
Carbon disulfide is prepared by heating sulfur and charcoal. the chemical equation is S2(g) + C(s) <---> CS2 (g) Kc = 9.40 at 900 K.
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Answer:
0.006 mol of CaCl2 are present
Explanation:
Use dimensional analysis for this:
60.0 mL CaCl2/1 * 1 L/1000 mL * 0.10 mol/1 L = 0.006 mol
If you were to write this as fractions out on paper, you'll see that all of the units will cancel out and you'll be left with moles of CaCl2.
**REMEMBER** that molarity (M) is talking about how many moles of that substance is present in one Liter of solvent.
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