Understanding Chemical Changes

• Chemical changes can be dangerous or magical.
• Magic Rocks or Chemical Gardens are formed when metal salts react with sodium silicate to create colored precipitates.
• The precipitates in chemical gardens form plant-like structures, hence the name.
• The chapter focuses on different types of chemical changes
• Understanding chemical changes enables control and improvements in life quality.

Section A - Chemical Changes Questions

• Question 1: Identifying a non-chemical reaction among options like exploding fireworks, milk souring, boiling water, or bread dough rising.
• Question 2: Determining the resulting compound when an element is burned in air.
• Question 3: Recognizing the commonality between respiration, combustion, and rusting.
• Question 4: Identifying the product that nitric acid can be used to create.

Questions on Properties and Indicators

• Question 5: Identifying a liquid based on its reaction with phenolphthalein and litmus paper.
• Question 6: Inferring indicator colors (P, Q, R) when added to pure water, based on pH color changes.
• Question 7: Deducing the nature of a red solid when heated strongly and produces a silvery liquid and a gas.
• Question 8: Determining a suitable substance to neutralize wasp venom given its alkaline nature.
• Question 9: Interpreting dye test results from plants on different substances to infer dye properties.
• Question 10: Recognizing an example of combustion among given reactions.
• Question 11: Identifying solutions W, X, Y, and Z based on their pH levels (1, 7, etc.).
• Question 12: Determining an additive to reduce acid rain's impact in a lake.
• Question 13: Identifying the reaction type when heating purple crystals leads to blackening and gas release.
• Question 14: Describing indicator colors (thymol blue, congo red, phenolphthalein) in pure water.
• Question 15: Identifying substances reacting with dilute hydrochloric acid to yield water and salt.
• Question 16: Determining which solutions, based on pH, will likely mix to produce a neutral pH.

pH and Chemical Process Questions

• Question 17: Determining the volume of alkaline solution needed to neutralize an acid based on a pH change graph.
• Question 18: Identifying the option that does not describe a chemical change.
• Question 19: Evaluating statements about gold-plating (electrolyte use, layer on plates, chemical change due to electricity).
• Question 20: Analyzing a graph showing hydrogen gas volume over time when zinc reacts with excess dilute hydrochloric acid.
• Question 21: Identifying an option that is not a chemical change.
• Question 22: Identifying substance Y in a chemical reaction: Sulfuric acid + Y → salt + water + carbon dioxide.
• Question 23: Identifying which gas is not released during the burning of fuels.
• Question 24: Deducing information from the heating of solid mercury oxide into mercury and oxygen.
• Question 25: Recognizing processes initiated by light presence.

Colour Change Questions

• Question 26: Determining which indicator is unsuitable for identifying a sugar solution from nitric acid, based on color changes in acidic, neutral, and alkaline solutions.
• Question 27: Identifying the NOT correct statement about a magnesium block added to dilute acid.
• Question 28: Determining the result when sulfuric acid is added to calcium carbonate regarding gas production.
• Question 29: Finding the statement that doesn't describe an acid property in solution.
• Question 30: Identifying the property of alkalis.
• Question 31: Finding the solution for which the three indicators will appear yellow using a table of three indicators showing pH values.
• Question 32: Determining what to use to identify the gaseous product of photosynthesis.

Reactions and Properties Questions

• Question 33: Identifying the type of chemical reaction when ethylene burns in oxygen.
• Question 34: Determines which solutions would have the lowest pH values.
• Question 35: Determining the solution formed after sulfuric acid reacts completely with iron(II) carbonate.
• Question 36:Determining how to know that the acid has been used up completely when sulfuric acid reacts completely with iron(II) carbonate.
• Question 37: Determining which substances most probably went through a chemical change upon heating out of four.
• Question 38: Determining which of the following indicators can be used to find out the strength of an acid or alkali.
• Question 39: Determining which acid is found in our stomach which can help in digesting food.
• Question 40: Determining if accidental swallowing of alkali will be treated by swallowing of an acid.

Section B - Chemical Changes and Electrolysis

• Question 1: Discusses the effect of electricity on water, breaking it into substances X and Y.
  • Part (a): Asks for the name of the process taking place.
  • Part (b): Requires the identification of elements X and Y.
  • Part (c): Asks whether water is a compound or a mixture based on the experiment.
• Question 2: Deals with dilute sulfuric acid reacting with green copper(II) carbonate, yielding a blue solution and gas.
  • Part (i): Asks what should be expected.
  • Part (ii): Requires a description of how the gas may be tested.

Acid Compounds/Everyday Life Groups

• Question 3: Word equation on the reaction of sulphuric acid + copper (II) carbonate.
  • Provide the definition of neutralisation and its application in everyday life
• Question 4: asks students to look at 2 groups of objects.
  • Name differences between the 2 groups.
• Question 5: Removing labels of 2 bottles (zinc / copper) find if the appearance will assist.

Physical and Chemical Properties/ Heating

• Question 4: Matter interaction that brings physical and chemical change.
  • Asking the differences between physical and chemical change.
  • Physical change interaction with heat.
  • Chemical change interactions with light.
• Question 5: Formulae on burning magnesium ribbon in air, heating copper (II) carbonate, and heating iron filings with sulphur.

Rusting Process, Factors and Equations

• Question 6: Four students investigating the factors that cause rusting of the nail.
  • Asking whether rusting is a chemical or physical change.
  • Name the process of rusting including the equations.
• Question 7: table on some information about heating copper and 2 compounds
  • Asking which substance remained unchanged after heating.
  • Write the reaction name for copper heating.
  • Discuss and write the decreasing mass equation for copper carbonate after heating.

Acids and Alkalis

• Question 8: Tom, testing acid and alkalis with plant extracts.
  • Asking to choose a plant extract not used as an indicator.
  • State what the colour changes will be when the geranium extract and sodium hydroxide.
  • State what the colour changes will be when the red cabbage extract and vinegar.
• Question 9: Student heating some substances to determine phase.
  • State an observation (with support) that shows physical change.
  • Explain the gas which magnesium ribbon reacted with and the name of the products forming.
• Question 10: Main ingredient in eggs tells is a calcium carbonate
  • Write calcium carbonate's formula.
  • Limestones formula equation.

Section C - Chemical Equations and Formulas

• Question 1:
  • The figure below shows some chemical reactions with Substance X and asks to identify the unknown substance or gas.
  • Identify substances X, Y, and Z
  • Name the reaction between substance X and potassium hydroxide
  • What are the colour changes, if any, when a Universal Indicator is added to Magnesium Chloride?
  • Conduct a chemical test for carbon dioxide gas.
  • If substance Z is soluble in water and easily decomposed by heat, how would a dry sample of substance Z be obtained.
  • If substance Z is soluble in water and stable to heat, how would a dry sample of substance Z be obtained.

Acids and Alkalines

• Question 2:
  • Discuss states of sodium nitrate (a salt) reacting an acid with an alkali
  • State the name of the reaction that occurs between the acid and alkali.
  • State an acid and an acid that is a form of sodium nitrate, with the formula.

Chemical Equations with Magnesium and Zinc

• Question 3: -Laboratory officer mixing beakers with powdered magnesium or zinc carbonate, describe the best equations or method to use to confirm.