9. Calculate the pH for each of the following cases in the titration of 35.0 mL of 0.200-M methylamine, CH3NH2(aq), with 0.200 M HCl(aq): (a) before addition of any HCl(aq) (b) after addition of 17.5 mL of HCl(aq) (c) after addition of 34.9 mL of HCl(aq) (d) after addition of 35.0 mL of HCl(aq) (e) after addition of 35.1 mL of HCl(aq)

a) pH = 11.97

b) pH = 10.66

c) pH = 7.96

d) pH = 5.83

e) pH = 3.7

Explanation:

a) The reaction is

CH₃NH₂ + H₂O = CH₃NH₃+ + OH-

b)

base left = 0.13 - 0.0667 = 0.066 M

c)

d) at equivalence point:

e)

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).