urgent please help!!

Question

anonymous · Answer

attachment

aaronq · Answer

17 is correct because pH is in a logarithmic scale

in fact the prefix  "p-" means "-log"

aaronq · Answer

acids have a pH of less than 7, [H+]>1.0x10^-7
pH =7 is considered neutral because [H+]=[OH-]=1.0x10^-7
bases have a pH higher than 7, [H+]<1.0x10^-7

anonymous · Answer

ok so what about 15?

anonymous · Answer

explain how i can get the  answer too not just giving me the answer

aaronq · Answer

there is no question 15 on that image

anonymous · Answer

oh oki thought it showed 1 sec

anonymous · Answer

What does the pH scale indicate?

A) the concentration of hydrogen ions
B) how much acid has been put into the water
C) how much water has dissociated
D) the concentration of hydronium ions
E) how much base has been put into the water

aaronq · Answer

pH is defined as the negative logarithm of the activity of the hydronium ion (more commonly as the concentration).. 

$$pH=-\log[H_3O^+]$$

aaronq · Answer

the square brackets [ ] mean concentration

aaronq · Answer

people often write it as [H+] which is incorrect because H+ doesn't exist free in solution, it's always bound to water.

2H2O <-> OH- + H3O+

anonymous · Answer

im thinking a?

aaronq · Answer

D) the concentration of hydronium ions

hydronium is H3O+

anonymous · Answer

ohh  so hydrogen is ??

aaronq · Answer

hydrogen ion can be either hydronium H3O^+  or hydride H^-, so it's ambiguous.

aaronq · Answer

the only problem is that high schools often call H+ the hydrogen ion, so since it's multiple choice you might get it wrong

anonymous · Answer

oh thank u for helping me once again!!!!!!!!!!!!!!!!!!!!! :)

aaronq · Answer

no problem !