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Hydrogen, Metals and Acids Topic Summary

Hydrogen, Metals and Acids Topic Summary

Key Vocabulary

  • Hydrogen: An essential element and the simplest of all the elements.

  • Metal: A solid material that is typically hard, shiny, malleable, fusible, and ductile.

  • Indicator: A substance that can help identify the pH of a solution.

  • pH: A scale used to specify the acidity or basicity of an aqueous solution.

  • Acid: A substance that has a pH of less than 7 and can donate protons (H+ ions).

  • Alkali: A basic, soluble hydroxide that has a pH greater than 7.

  • Base: A substance that can accept protons or donate electron pairs in reactions.

  • Non-metal: An element that is typically a poor conductor of heat and electricity.

  • Concentration: The amount of a substance in a given volume or mass.

  • Displacement: A reaction in which one element displaces another in a compound.

  • Oxidation: The process of losing electrons or an increase in oxidation state by a molecule, atom, or ion.

  • Reactivity: The tendency of a substance to undergo chemical reaction.

Skills

Using Equipment Correctly

  • Bunsen burner: For heating substances.

  • Balance: To measure mass accurately.

  • Indicators: To determine pH changes in solutions.

  • Measuring cylinder: For accurate volume measurements.

  • Reading scales: To interpret measurements accurately.

Writing Up Experiments

  • Diagrams: Essential for representing setups and processes visually.

  • Tables: For organizing data systematically.

  • Graphs: For visualizing relationships between data sets.

  • Risk assessments: Evaluate potential hazards in experiments.

  • Identifying variables: Recognize the independent, dependent, and control variables in an experiment.

  • Interpreting observations: Analyze and discuss reactions as they occur.

  • Conclusions: Draw conclusions from experimental results.

Writing Word Equations for Reactions

  • (For electrolysis) water → hydrogen + oxygen

  • Hydrogen + oxygen → water

  • Metal + water → metal hydroxide + hydrogen

  • Metal + acid → salt + hydrogen

  • Acid + carbonate → salt + water + carbon dioxide

Salt Creation

  • Hydrochloric Acid: Produces salts called Chlorides.

  • Sulfuric Acid: Produces salts called Sulfates.

  • Nitric Acid: Produces salts called Nitrates.

Gas Tests

Gas

Test

Result

Hydrogen

Lighted spill

Squeaky pop

Carbon Dioxide

Bubble through lime water

Lime water goes cloudy

Oxygen

Glowing spill

Spill re-lights

pH Scale and Indicators

  • The pH scale is a measure of how acidic or alkaline a solution is, ranging from 0 to 14:

    • Acids: pH < 7

    • Alkalis: pH > 7

    • Neutral: pH = 7 (e.g., water, salts)

Indicators

  • Indicators change color based on the pH of a solution.

    • Universal Indicator: A mixture that shows a range of colors depending on the pH.

    • Litmus Paper: Changes color but may not correspond to the universal indicator’s colors.

    • Red Cabbage Indicator:

    • To make it: Roughly chop the cabbage, heat in boiling water, and filter out the solid.

Neutralization

  • Adding an alkali to an acid shifts the pH toward neutral initially and can overshoot to a more alkaline state.

  • Adding an acid to an alkali also shifts the pH towards neutral and may become increasingly acidic.

Observations During Reactions

  1. Effervescence: Production of gas bubbles.

  2. Changes in energy: Light, sound, temperature change, or explosion.

  3. Consumption: A solid disappearing during the reaction (e.g., metal dissolving in acid).

  4. Formation of a new substance: Changes in color or other observable physical properties.