Question

These exercises deal with logarithmic scales.

The hydrogen ion concentration of a sample of each substance is given. Calculate the pH of the substance.

Answer 1

\[Ph=-\log(H^+)\]?

Answer 2

if i remember but this may be wrong. if so you get for the first one
\[-\log(5\times 10^{-3})=\log(5)-\log(10^{-3})=-\log(5)-(-3)=3-\log(5)\]

Answer 3

that is the full process when you show work for number 1?

Answer 4

yes. assuming the formula i wrote is correct. i get about 2.3 as a decimal

Answer 5

actually the answer is right but i made a typo. it should be
\[-\log(5\times 10^{-3})=-\log(5)-\log(10^{-3})=-\log(5)-(-3)=3-\log(5)\]

Answer 6

but i repeat make sure the formula is right. you did not post it, i just looked it up.

Answer 7

you are correct in that formula.

Answer 8

what did you get for the other 2?

Answer 9

next one would be
\[4-\log(3.2)\] and last one would be
\[9-\log(5)\]

Answer 10

would it be to much to ask for how you got those. like could you show me the work

Answer 11

for those 2

Answer 12

cause it says that b) should be 3.5 and c) should be 8.3

Answer 13

yes that looks right. i just gave you the formula. if you want a decimal you have to use a calculator.

Answer 14

can you show me the steps for b and c

Answer 15

\[4-\log(3.2)=3.494...\]
\[9-\log(5)=8.3...\]

Answer 16

sure it is the same as before

Answer 17

how did you get to that point for those 2 i mean i need to be able to write it all out

Answer 18

you have
\[pH=-\log(a\times 10^b)=-(log(a)+\log(10^b)=-(\log(a)+b)=-b-\log(a)\]\]
\[=

Answer 19

lets look at it simply

Answer 20

\[\log(5\times 10^{-9})=\log(5)+\log(10^{-9})=\log(5)-9\]
are those steps clear?

Answer 21

first step because
\[\log(ab)=\log(a)+\log(b)\] aways

Answer 22

second step because
\[\log(10^x)=x\]

Answer 23

now you want the negative of that, and the negative of
\[\log(5)-9\] is
\[9-\log(5)\]

Answer 24

so if i want the pH of
\[7\times 10^{-11}\] i go right to the answer of
\[pH=11-\log(7)\]

Answer 25

of course i need a calculator to find the decimal

Answer 26

10.155

Answer 27

ok fine. i just made up that example but i hope you see how it works. except for the actual calculator work you can almost do it in your head

Answer 28

thanks for your help

Answer 29

i have one more that estudier cant figure out

Answer 30

thats my only other question i have no idea how to do it

Answer 31

where? i will look