Chemistry ATP Revision Notes Practice Flashcards

A set of practice Q&A flashcards based on the Chemistry ATP revision notes covering laboratory techniques, equipment, ion testing, and experimental observations.

What is the purpose of using ice or cold water in a laboratory experiment?

To cool down the gas so that it condenses and turns into a liquid.

If a gas collecting tube is positioned upside down, what property of the gas is being indicated?

The gas is less dense than air.

Why is a pencil used to draw the origin line in chromatography instead of a pen?

If a pen was used, the ink would dissolve and interfere with the results, making the experiment inaccurate.

What precaution should be taken when using ethanol in an experiment, and why?

Cover the apparatus with a lid because ethanol is volatile.

In an observation table, if heating a solid results in condensation, what does this indicate about the solid?

The solid is hydrated.

What is the best 4-mark description for the observation when copper is used in a chemical test?

A light blue precipitate (ppt) forms, which is soluble in excess to form a dark blue solution.

Why are certain experiments conducted in a fume cupboard?

Because the experiment releases harmful/toxic gases that are poisonous.

In a graph, how can you identify an inaccurate result?

It is a point that does not fall on the drawn graph line; you should identify its x-axis value and state it does not occur in the graph trend.

Why should a solid be crushed before a reaction?

To increase the surface area for a faster rate of reaction.

Why is it necessary to conduct certain experiments in a well-ventilated room?

To prevent the burning of the substance.

What does the term 'decant' mean?

To filter or pour the liquid out while leaving the solid behind.

Why is concentrated sulphuric acid ($H_2SO_4$) not used to dry ammonia ($NH_3$)?

Because it will react with the base ammonia in a neutralization reaction.

Why should soil samples be taken from different parts of a field?

To obtain more accurate results.

What are the two requirements for iron to rust?

Water (humidity) and oxygen (air).

Why does the water level increase in a closed experiment involving the rusting of iron?

Oxygen is used up during the reaction, and water moves to take its place.

What are three common observations during electrolysis?

1. The bulb will light. 2. A metal is formed on the cathode. 3. Fizzing or effervescence of gases produced.

Suggest suitable materials for use as electrodes.

Graphite, Carbon, Steel, or Platinum.

What color change occurs when copper oxide ($CuO$) reacts with hydrogen?

The color changes from black to brown because copper oxide is reduced to copper.

How can you distinguish between water ($H_2O$) and ethanol ($C_2H_5OH$)?

Use cobalt chloride paper; it turns from pink to blue with water, but shows no change with ethanol.

How can you distinguish between hydrochloric acid ($HCl$) and nitric acid ($HNO_3$)?

Add silver nitrate ($AgNO_3$); a white precipitate will form with hydrochloric acid, but there will be no reaction with nitric acid.

What is the purpose of mineral wool in specific experimental setups?

To absorb and hold the liquid.

What precaution must be taken when removing heat from an experiment involving a delivery tube?

Remove the delivery tube from the water to prevent suck-back.

What key phrase should always be included when discussing the rate of reactions?

"Collisions between particles".

How can you distinguish between an alkene and an alkane?

Use bromine water; the alkene will decolourise it from orange to colourless, while no change occurs with an alkane.

How can you distinguish between chlorine and sodium chloride ($NaCl$)?

Add litmus paper; it will be bleached by chlorine, but remain unchanged by sodium chloride.

How can you distinguish between copper sulphate ($CuSO_4$) and copper carbonate ($CuCO_3$)?

Add hydrochloric acid ($HCl$); nothing happens with the sulphate, but fizzing/effervescence of $CO_2$ occurs with the carbonate.

If a measuring cylinder is used, what apparatus change could make the results more reliable?

Using a burette because it is more accurate.

What is the relationship between the concentration of a reagent and the volume needed for a reaction?

The volume of reagent used decreases if it is more concentrated.

What are the pH ranges for strong and weak acids?

A strong acid is between $pH$ $0$ and $2$; a weak acid is between $pH$ $3$ and $6$. ($7$ is neutral).

What are the pH ranges for strong and weak bases?

A weak base is between $pH$ $8$ and $11$; a strong base is between $pH$ $12$ and $14$.

Define a strong acid.

An acid that ionizes completely to give $H^+$ ions in solution.

What is the definition of a saturated solution?

A solution where no more solute can be dissolved in a solvent at a constant temperature.

How can you detect the point of crystallization?

Place a stirring rod in the solution and observe the formation of the first crystals on it.

Why is grass ground with ethanol rather than water to extract chlorophyll?

Chlorophyll is more soluble in ethanol than in water.

What is the action of a Liebig condenser?

To change steam into water (condensation).

How can you check the purity of a collected solvent?

Test its melting or boiling point.

Why must amino acid chromatograms be sprayed with a locating agent?

Because amino acids are colourless and need to be made visible.

What is the color change of hydrated copper sulphate when heated?

It turns from blue to white.

Why are some crystals dried using filter paper instead of heating?

To prevent the complete loss of water from the crystals and to prevent the crystals from breaking.

Give the chemical test for water.

Add blue cobalt chloride paper (turns pink) OR add anhydrous copper sulphate (turns blue).

Why should a water bath be used when heating alcohol?

Alcohol is flammable; if it touches a lighted splint, it will catch fire.

What is the accurate volume measurement for a standard burette?

$$50\,cm^3$$

Describe the method 'Downward displacement of air'.

Used for gases more dense than air, such as Carbon dioxide, Chlorine, Sulphur dioxide, and Hydrogen chloride.

Describe the method 'Upward displacement of air'.

Used for gases less dense than air, such as Ammonia and Hydrogen.

Which salts are always soluble?

All nitrates and all sodium, potassium, and ammonium salts.

What is the test for the Aluminum ion ($Al^{3+}$) using Sodium Hydroxide ($NaOH$)?

A white precipitate forms which dissolves in excess $NaOH$ to give a colourless solution.

What is the test for Carbonate ions ($CO_3^{2-}$)?

Add dilute $HCl$; $CO_2$ is released which turns limewater milky.

What is the formula for the $R_f$ value in chromatography?

$$R_f\,Value = \frac{\text{Distance moved by solute}}{\text{Distance moved by solvent}}$$

What color does Lithium produce in a flame test?

Red

What color does Potassium produce in a flame test?

Lilac

What color does Sodium produce in a flame test?

Yellow