4.48
pH=pKa+log([A-/HA])
25% deprotonated tells us that A- is .25 and that the rest (75% is protonated) thats .75.
4 = pKa + log \frac{.25}{.75}
4 - log \frac{.25}{.75} = pKa
4.48=pKa
<span>stereochemistry and reaction mechanisms</span>
Answer:Why does weathering cause erosion
Explanation:Organic weathering happens when plants break up rocks with their growing roots or plant acids help dissolve rock. Once the rock has been weakened and broken up by weathering it is ready for erosion. Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity.
D is the only choice here that is appropriate given neutrons' lack of charge
Answer:
The solution would need 13.9 g of KCl
Explanation:
0.75 m, means molal concentration
0.75 moles in 1 kg of solvent.
Let's think as an aqueous solution.
250 mL = 250 g, cause water density (1g/mL)
1000 g have 0.75 moles of solute
250 g will have (0.75 . 250)/1000 = 0.1875 moles of KCl
Let's convert that moles in mass (mol . molar mass)
0.1875 m . 74.55 g/m = 13.9 g