Acids, bases and pHIB MYP Sciences: Flashcards

Exam questions on Acids, bases and pH

1. Students at a school in Nairobi are sorting four household liquids using universal indicator solution. Lemon juice turned the indicator orange-red, tap water turned it green, a baking-soda solution turned it blue and oven cleaner turned it deep purple.
   Explain why universal indicator is more useful than litmus paper for comparing the lemon juice with a stronger acid.2 marks
2. A technician at a school in Lisbon is preparing to dilute a bottle of concentrated hydrochloric acid and a bottle of sodium hydroxide solution for a practical lesson. Both bottles carry the corrosive hazard symbol.
   Suggest two safety precautions the technician should take when handling the concentrated solutions.2 marks
3. Priya, a student in Mumbai, wants to compare how well three brands of indigestion tablet (P, Q and R) neutralise acid. Each tablet contains a base. She crushes one tablet at a time, adds it to 50 cm³ of dilute hydrochloric acid containing universal indicator, stirs, and keeps adding tablets until the indicator turns green. She records the number of tablets needed. Brand P needed 3 tablets, brand Q needed 5 tablets and brand R needed 2 tablets. She did each test once and concludes that brand R is the best.
   State a testable hypothesis for Priya's investigation, with a scientific reason, and identify the independent variable and the dependent variable.3 marks