Investigation of Acidic, Neutral and Alkaline Substances

Results:

Substance	Blue Litmus		Red Litmus		Universal indicator (pH)
	Prediction	Result	Prediction	Result	Prediction	Result
Orange Juice	Red	Red	Red	Red	3	5
Oat Milk	Red	Blue	Red	Blue	6	8
Water	Blue	Blue	Red	Red	7	7
Washing Up Liquid	Blue	Blue	Blue	Red	9	7
Laundry Detergent	Blue	Blue	Blue	Blue	9	8
Vinegar	Red	Red	Red	Red	2	4
Mouthwash	Blue	Blue	Blue	Red	8	7

Conclusion:

Both orange juice and vinegar turned the blue litmus paper red and left the red litmus paper its original colour. Meanwhile, the oat milk and laundry detergent had the opposite effect, leaving the blue litmus unchanged and turning the red litmus blue. Three substances left both the red and blue litmus the same colour: water, washing up liquid and mouthwash.

This shows that orange juice and vinegar are acidic. As they have the pH of 5 and 4 respectively, they are also weak acids. Meanwhile, the results show that oat milk and laundry detergent are weak alkalis, both having a pH of 8. The results also show that water, washing up liquid and mouthwash all have a pH of 7, meaning that they are neutral.

Nearly all of the predictions for the blue litmus paper were correct with only oat milk being wrong. Meanwhile, 3 of the predictions for the red litmus were incorrect: oat milk, washing up liquid and mouthwash. Overall, the predictions for the Universal indicator were slightly more acidic or alkaline than the substances turned out to be. However, the prediction for water was correct.

All three drinks were not strongly acidic or alkaline, with orange juice, water and oat milk having a pH of 5, 7 and 8 respectively. The cleaning products all have a similar pH: washing up liquid is 7 and laundry detergent is slightly more alkaline with a pH of 8. Another similarity is between the substances that you put in your mouth. They are all either weak acids (orange juice and vinegar), neutral substances (water and mouthwash) or weak alkalis (oat milk).