Questions and Answers
What does a pH of 7 indicate about a solution?
Diluting an acid will decrease its pH towards 7.
False
Name one nutrient that is commonly found in fertilizers.
Nitrogen
A _____ is composed of the same substance throughout, whereas a _____ is made up of two or more minerals.
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Match the type of rock with its formation process:
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Which of these is used for measuring the pH of a solution most accurately?
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Red cabbage can be used as a pH indicator.
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What process is used to extract copper from malachite?
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Which of the following is a common characteristic of acids?
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Universal indicators turn blue in acidic solutions.
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What are the three main elements commonly found in fertilizers?
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The process of heating a metal ore with carbon to extract metals is called __________.
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Match the type of rock with its description:
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Which of the following statements about pH and dilution is correct?
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Rocks consist of a single type of mineral.
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Name one use of pH probes.
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A __________ reaction occurs when a more reactive element displaces a less reactive element from a compound.
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Which of the following is an example of an unreactive metal found in the Earth's crust?
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Study Notes
Acids and Alkalis
- pH measures the concentration of Hydrogen ions (H+) in a solution, indicating its acidity or alkalinity.
- Examples of alkalis include cleaning products like bleach; some foods and drinks are acidic.
- Testing the pH of substances is most accurate when dissolved in water.
pH Indicators
- pH indicators are chemicals that change color to reflect pH levels of a solution.
- Universal indicator and pH paper show red in acids, green in neutral solutions, and dark blue in alkalis.
- Red cabbage is an example of a natural pH indicator.
- Diluting acids increases pH towards 7, while diluting alkalis decreases pH towards 7.
- pH probes provide exact digital readings of pH and are the most accurate measurement tools.
Fertilisers
- Fertilisers enhance plant production by adding essential nutrients to soil.
- Key nutrients in fertilisers include Potassium, Nitrogen, and Phosphorus.
- Fertilisers are typically created through the reaction between an acid and an alkali.
Rocks and Minerals
- The Earth is comprised of rocks and minerals, with minerals being uniform substances and rocks consisting of multiple minerals.
- Igneous rocks form from cooling and solidification of hot liquid rock (magma).
- Metal ores are specific rocks that contain metal compounds.
- Unreactive metals like gold exist in their elemental form in the Earth's crust, while others like copper and iron require extraction methods.
- Copper can be extracted from malachite through successive heating processes, first with heat alone and then with carbon.
Displacement Reactions
- Displacement reactions refer to processes where one element displaces another in a compound, often observed in metal extractions.
Corrosion
- Corrosion is the degradation of materials (usually metals) due to chemical reactions, particularly with oxygen and moisture in the environment.
Acids and Alkalis
- pH measures Hydrogen ion concentration in a solution, indicating acidity or alkalinity.
- Common cleaning products like bleach are alkaline, while various foods and drinks can be acidic.
- Solutions should be dissolved in water prior to pH testing for accurate results.
pH Indicators
- pH indicators are chemicals that exhibit color change to depict the pH level of a solution.
- Universal indicator and pH paper show red in acidic solutions, green in neutral, and dark blue in alkaline solutions.
- Red cabbage can be used as a natural pH indicator.
- Dilution of acids increases pH towards 7, making them less acidic; dilution of alkalis decreases pH towards 7, making them less alkaline.
- pH probes provide the most precise measurement of pH, delivering an exact digital readout.
Fertilisers
- Fertilisers enhance plant growth by adding essential nutrients to the soil.
- Key elements in fertilisers include Potassium, Nitrogen, and Phosphorus.
- Most fertilisers are produced through the reaction of an acid with an alkali.
Rocks and Minerals
- The Earth consists of rocks and minerals, where a mineral is a uniform substance and a rock is composed of multiple minerals.
- Igneous rocks are formed from the cooling and solidification of magma.
- Metal ores contain metal compounds, and unreactive metals like gold occur uncombined in the Earth's crust.
- Reactive metals, such as copper and iron, require extraction methods like heating alone or heating with carbon.
- Copper can be extracted from malachite through a two-step heating process.
Displacement Reactions
- Involve the replacement of one element in a compound by another element.
Corrosion
- Destructive process where metals degrade due to chemical reactions with environmental elements, commonly water and oxygen.
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Description
Test your knowledge on Environmental Chemistry focusing on acids, alkalis, and pH indicators. This quiz will cover important concepts such as pH measurement and the use of indicators to determine acidity or alkalinity in various solutions. Perfect for S2 Science students!
