Testing the pH of Common Household Substances Lab by cuiliqing


          Testing the pH of Common
          Household Substances Lab
                 Mehwesh Tariq
               Ms. Tran

               Testing the pH of Common Household Substances Lab

Background Information:

The pH scale is used to determine the acidity or basicity level of liquid solutions. If a solution
scores a pH level of 1-6 it is an acidic solution, 1 being the most acidic and 6 being the least
acidic. If a solution rates a pH level of 7 it is a neutral solution, meaning it is neither an acidic
nor a basic solution. Lastly, if a solution is 8-14 on the pH scale it is a basic solution, 8 being the
least basic and 14 being the most basic. The products that are used on a daily basis in your house
can also be acidic solutions, basic solutions, or even neutral solutions.


Food products are likely to be weak acids because food is not slippery, you can eat it which is
why it’s a weak acid, and because foods are sour. Cleaning products are predicted to be strong
bases because they consist of a very key characteristic of bases; they are slippery. Personal care
products are predicted to be neutral solutions because they are not corrosive like acids and bases
that can harm your skin.


      12-well dish
      Paper indicators
          o Red litmus
          o Blue litmus
          o pH paper
      Various common household substances
          o Shampoo
          o Lemon juice
          o Green tea
          o Sprite
          o Detergent
          o Milk
          o Windex

   1. Obtain a small sample of each substance to be tested. Place the substance in one well of
      the 12-well dish.
   2. Test the effect of each sample on red litmus and blue litmus to determine if the
      substance is acidic, basic or neutral. (Make sure if you have a substance from EACH
      product type)
   3. Test each sample with universal indicator paper. Match the color of the universal
      indicator paper with the indicator chart to determine the approximate pH value of the
      substance. Record the pH value and classify the substance as a:
           strong base (pH=11-14)
           weak base (pH=8-10)
           approximately neutral (pH=7)
           weak acid (pH=4-6)
           strong acid (pH=0-3)


Substance      Product      Red           Blue           pH Paper      pH Value      Analysis
               Type         Litmus        Litmus                                     Acid or
Shampoo        Personal     Stayed Red    Pink           Stayed        pH 4          Weak Acid
               Care                                      Orange
Lemon          Food         Stayed Red    Red            Bright Red    pH 1          Strong
Juice                                                                                Acid
Green Tea      Food         Stayed Red    Stayed         Stayed        pH 7          Neutral
                                          Blue           Orange
Sprite         Food         Stayed Red    Pink           Stayed        pH 4          Weak Acid
Milk           Food         Light         Stayed         Yellow        pH 7          Neutral
                            Purple        Blue
Detergent      Cleaning     Blue          Stayed         Yellow        pH 10         Base
Windex         Cleaning     Blue          Stayed         Light         pH 9          Weak Base
                                          Blue           Green


The three classes of household products tested for pH levels in this lab were; cleaning, personal
care, and food products. The only personal care product that was tested in this lab was shampoo;
which was a very weak acid, it scored 4 on the pH scale, when tested with red litmus it stayed
red, but turned pink when tested with blue litmus and stayed orange when tested with pH paper.
Lemon juice was the first food product tested it proved to be a very strong acid; red litmus stayed
the same color, blue litmus turned red and pH paper turned bright red, scoring a 7 on the pH
scale. The second food product that was tested was green tea which was neutral; it stayed red
with red litmus, stayed blue with blue litmus and stayed orange with pH paper and therefore,
scored a pH level of 7. The third food product that was tested was Sprite, which was a weak acid,
the red litmus stayed red, blue litmus turned pink and the pH paper stayed orange scoring a pH
level of 7. The last food product that was tested was milk, which turned out to be neutral, when
tested with red litmus it turned light purple, the blue litmus stayed blue and the pH paper turned
yellow, which scored a pH level of 7. Lastly, cleaning products were tested. The first cleaning
product tested was detergent which was a base, the red litmus turned blue, the blue litmus stayed
blue and the pH paper turned yellow, giving it a pH level of 10. The last cleaning product tested
was Windex which was a weak base; it turned red litmus blue, kept blue litmus the same color
and turned pH paper light green and scored a pH level of 9.


When red litmus paper was tested on substances from the food category they stayed red, except
for milk which turned light purple. When tested with blue litmus paper the results varied; lemon
juice was red-because it’s an acid, green tea and milk stayed blue-because they’re neutral and -
Sprite turned pink-because it’s a weak acid. The results also varied when tested with pH paper;
lemon juice turned bright red-because it’s a strong acid, green tea and Sprite stayed orange and
milk turned yellow-because it’s a base.

Only one personal care product was tested; shampoo. It showed acidic properties when tested
with all three indicators; the red litmus stayed red, the blue litmus turned pink and the pH paper
stayed orange. Shampoo resulted to be a weak acid.

The results for cleaning products were very similar. When tested with red litmus detergent and
Windex both turned the paper blue. Then, when they were tested with blue litmus both products
kept the blue litmus the same color. The only result that varied was when tested with pH paper
detergent turned the paper yellow, while Windex turned the paper light green. But in the end they
were both bases, just one stronger than the other.

    1. Most of the results within the product class are the same, but the results differ within the
       class of food products. Food products vary from being acids and neutral solutions. Food
       products which are sour, like lemon juice, turn out to be acids. On the other hand, some
       food products are neutral such as milk and green tea.
    2. Most of the household products are acids, but in general whichever category they fall
       under they are weak. The reason the acids are weak because these are things that you use
       in your day-to-day life, if the acidity level is high it can burn through your skin and
       cause harm. On the other hand, the cleaning products are weak bases because they need
       to have some acidic properties to them in order to kill bacteria, if it was a strong base it
       would not have the same affect.
    3. There are many possible errors that could have occurred. First, when putting the chosen
       substance in the 12-well dish, the wooden stick that was touching the substance may
       have been contaminated with another substance. Secondly, when all the substances were
       in the 12-well dish, it was possible that one substance could have accidentally touched
       another substance. Another error that could have occurred is that enough time was not
       given to see the change of color in the various indicator papers. Also if a person’s fingers
       were contaminated with another acid, base, or neutral solution it could have altered the
       pH level found for the substance. To ensure the best and most accurate results this
       experiment could be conducted once more.


                                                                      12-Well Dish
                                                                      Blue Litmus Paper
                                                                      Red Litmus Paper
                                                                      pH Paper
                                                                      Lemon Juice
                                                                      Green Tea

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