Question

Help please! On a deadline. Posting below

Answer 1

Chemists define the acidity or alkalinity of a substance according to the formula pH = –log[H+] where [H+] is the hydrogen ion concentration, measured in moles per liter. Solutions with a pH value of less than 7 are acidic; solutions with a pH value of greater than 7 are basic; solutions with a pH of 7 (such as pure water) are neutral.

Answer 2

a) Suppose that you test apple juice and find that the hydrogen ion concentration is [H+] = 0.0008. Find the pH value and determine whether the juice is basic or acidic.
b) You test some ammonia and determine the hydrogen ion concentration to be [H+]= 1.7 × 10–8. Find the pH value and determine whether the ammonia is basic or acidic.

Answer 3

@paki @sammixboo

Answer 4

pH = - log[H+]

just plug in value of H+

Answer 5

and use your calculator to work it out
the log is log to base 10

Answer 6

@Mehek14 @EclipsedStar

Answer 7

hint:
\[\log 0.0008 = - 3.0969\]

Answer 8

sorry can't help right now :/

Answer 9

@Godlovesme

Answer 10

@Lady.Liv1776

Answer 11

welll , i can help

Answer 12

PH = -log[H+], plug in the concentration of the H+

Answer 13

i dont have one clue how to do this

Answer 14

just plug in the concentration which is [H+] , -log[H+]

Answer 15

got it @Ogziii

Answer 16

how much did you get ? (the PH ) ?

Answer 17

all i did was write down -log[H+] . How do you get the ph?

Answer 18

use your calculator , you'll find a log on it , now write down , - log [0.0008] , you'll get a number , thats the PH

Answer 19

I got this:
pH=-(-3.0969)=3.0969

Answer 20

How'd you get that? @Michele_Laino Thing is, i dont have a calculator.

Answer 21

you'll need for a calculator to solve such things ( in the class ) , you could use an online calculator http://web2.0calc.fr/ ,

Answer 22

please use Windows calculator

Answer 23

Got it @Ogziii now what

Answer 24

now , write , - log [0.0008], you'll get your ph , if it is higher than 7 , it's a base , if it is lower than 7 it's an acid ,

Answer 25

its an acid

Answer 26

now what @Ogziii

Answer 27

@Michele_Laino

Answer 28

thats all , its an acid is the answer to a ) , now apply the same rule to b , you'll get your answer

Answer 29

its different from a

Answer 30

yes , but same rule , -log[H+] , just plug in the new concentration instead of the juice's concentration , you'll get a new PH value , it will determine the answer

Answer 31

ughh, i dont know why i find this so confusing.

Answer 32

for question b. we have:
\[\log \left( {1.7 \times {{10}^{ - 8}}} \right) = - 8 + \log \left( {1.7} \right) = - 7.7696\]
so:
pH=-(-7.7696)=...?

Answer 33

i guess that we're not supposed to give answers , am i right ? xD

Answer 34

it'd be 7.7696?