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chemistry > chemical reactions and equations > Flashcards

chemical reactions and equations Flashcards

1
Q

What is a chemical reaction?

A

A process that leads to the transformation of one set of chemical substances to another. Involves the breaking and forming of chemical bonds.

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2
Q

What are reactants?

A

The substances that take part in a chemical reaction (the starting materials).

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3
Q

What are products?

A

The substances formed as a result of a chemical reaction.

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4
Q

What is a chemical equation?

A

A symbolic representation of a chemical reaction using chemical formulas and symbols.

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5
Q

What is a balanced chemical equation?

A

A chemical equation in which the number of atoms of each element is equal on both the reactant and product sides. Obeys the Law of Conservation of Mass.

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6
Q

What is the Law of Conservation of Mass?

A

Matter can neither be created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.

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7
Q

What does the arrow (→) in a chemical equation represent?

A

Indicates the direction of the reaction, usually from reactants to products.

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8
Q

What are the symbols (s), (l), (g), and (aq) used for in a chemical equation?

A

(s) - solid, (l) - liquid, (g) - gas, (aq) - aqueous solution (dissolved in water)

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9
Q

What is a combination reaction (or synthesis reaction)?

A

Two or more reactants combine to form a single product.

Example: A + B → AB

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10
Q

What is a decomposition reaction?

A

A single reactant breaks down into two or more simpler products.

Example: AB → A + B

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11
Q

What is a displacement reaction?

A

A more reactive element displaces a less reactive element from its compound.

Example: A + BC → AC + B

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12
Q

What is a double displacement reaction?

A

Two reactants exchange ions or groups of ions to form two new products.

Example: AB + CD → AD + CB

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13
Q

What is a precipitation reaction?

A

A double displacement reaction in which one of the products is an insoluble solid (a precipitate).

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14
Q

What is an exothermic reaction?

A

A reaction that releases heat to the surroundings. ΔH is negative.

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15
Q

What is an endothermic reaction?

A

A reaction that absorbs heat from the surroundings. ΔH is positive.

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16
Q

What is a redox reaction?

A

A reaction involving both oxidation and reduction.

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17
Q

What is oxidation?

A

Loss of electrons or increase in oxidation number.

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18
Q

What is reduction?

A

Gain of electrons or decrease in oxidation number.

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19
Q

What is corrosion?

A

The gradual deterioration of a material, usually a metal, due to a chemical reaction with its environment (e.g., rusting of iron).

20
Q

What is rusting of iron?

A

A specific type of corrosion where iron reacts with oxygen and moisture to form hydrated iron(III) oxide (rust).

21
Q

What is rancidity?

A

The oxidation of fats and oils, leading to unpleasant smells and tastes.

22
Q

How can corrosion be prevented?

A

By preventing contact with oxygen and moisture (e.g., painting, galvanizing, electroplating).

23
Q

How can rancidity be prevented?

A

By adding antioxidants, storing food in airtight containers, refrigeration.

24
Q

Balance the following chemical equation: CH₄ + O₂ → CO₂ + H₂O

A

CH₄ + 2O₂ → CO₂ + 2H₂O (Count the atoms of each element on both sides and adjust the coefficients to make them equal.)

25
Q

What are some observable characteristics that suggest a chemical reaction has occurred?

A

Change in state (solid, liquid, gas), change in color, evolution of a gas (bubbles), change in temperature (heat produced or absorbed), formation of a precipitate (solid).

26
Q

Activity: Burning a magnesium ribbon. What is observed?

A

A bright white flame is produced, and a white powder (magnesium oxide) is formed. This indicates a chemical reaction (combination).

27
Q

Activity: Reaction between lead nitrate and potassium iodide. What is observed?

A

A yellow precipitate (lead iodide) is formed. This is a double displacement/precipitation reaction.

28
Q

Activity: Reaction between zinc granules and dilute hydrochloric acid. What is observed?

A

Bubbles of hydrogen gas are evolved, and the zinc granules dissolve. The test tube becomes warm (exothermic).

29
Q

Activity: Heating copper carbonate. What is observed?

A

A green solid (copper carbonate) turns black (copper oxide), and a colorless gas (carbon dioxide) is evolved.

30
Q

Activity: Combination reaction (example).

A

Burning of magnesium ribbon (2Mg + O₂ → 2MgO) or the reaction of quicklime with water (CaO + H₂O → Ca(OH)₂).

31
Q

Activity: Decomposition reaction (example).

A

Heating of calcium carbonate (CaCO₃ → CaO + CO₂) or heating lead nitrate.

32
Q

Activity: Displacement reaction (example).

A

Reaction of iron nails with copper sulfate solution (Fe + CuSO₄ → FeSO₄ + Cu). The blue color fades, and a reddish-brown deposit (copper) forms on the iron nail.

33
Q

Activity: Double displacement reaction (example).

A

Mixing solutions of lead nitrate and potassium iodide (Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃).

34
Q

Activity: Exothermic reaction (example).

A

Reaction of quicklime with water (CaO + H₂O → Ca(OH)₂). The mixture becomes hot.

35
Q

Activity: Endothermic reaction (example).

A

Dissolving ammonium chloride in water. The solution becomes cold.

This is often demonstrated, but not always a core activity.

36
Q

Activity: Burning a magnesium ribbon. What chemical change occurs?

A

Magnesium (Mg) combines with oxygen (O₂) in the air to form magnesium oxide (MgO). This is a new substance with different properties.

(2Mg + O₂ → 2MgO)

37
Q

Activity: Reaction between lead nitrate and potassium iodide. What chemical change occurs?

A

Lead nitrate (Pb(NO₃)₂) reacts with potassium iodide (KI) to form lead iodide (PbI₂) and potassium nitrate (KNO₃). The yellow precipitate is the lead iodide.

(Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃)

38
Q

Activity: Reaction between zinc granules and dilute hydrochloric acid. What chemical change occurs?

A

Zinc (Zn) reacts with hydrochloric acid (HCl) to produce zinc chloride (ZnCl₂) and hydrogen gas (H₂).

(Zn + 2HCl → ZnCl₂ + H₂)

39
Q

Activity: Heating copper carbonate. What chemical change occurs?

A

Copper carbonate (CuCO₃) decomposes into copper oxide (CuO) and carbon dioxide (CO₂).

(CuCO₃ → CuO + CO₂)

40
Q

Activity: Combination reaction (example with chemical change).

A

Burning of magnesium ribbon: Magnesium (Mg) and oxygen (O₂) combine to form magnesium oxide (MgO).

(2Mg + O₂ → 2MgO)

41
Q

Activity: Decomposition reaction (example with chemical change).

A

Heating of calcium carbonate: Calcium carbonate (CaCO₃) breaks down into calcium oxide (CaO) and carbon dioxide (CO₂).

(CaCO₃ → CaO + CO₂)

42
Q

Activity: Displacement reaction (example with chemical change).

A

Reaction of iron nails with copper sulfate solution: Iron (Fe) displaces copper (Cu) from copper sulfate (CuSO₄), forming iron sulfate (FeSO₄) and solid copper.

(Fe + CuSO₄ → FeSO₄ + Cu)

43
Q

Activity: Double displacement reaction (example with chemical change).

A

Mixing solutions of lead nitrate and potassium iodide: Lead nitrate (Pb(NO₃)₂) and potassium iodide (KI) exchange ions to form lead iodide (PbI₂) and potassium nitrate (KNO₃).

(Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃)

44
Q

Activity: Exothermic reaction (example with chemical change).

A

Reaction of quicklime with water: Calcium oxide (CaO) reacts with water (H₂O) to form calcium hydroxide (Ca(OH)₂) and releases heat.

(CaO + H₂O → Ca(OH)₂)

45
Q

Activity: Endothermic reaction (example with chemical change).

A

Dissolving ammonium chloride in water: Ammonium chloride (NH₄Cl) dissociates into ammonium ions (NH₄⁺) and chloride ions (Cl⁻) in water, absorbing heat from the surroundings.

(NH₄Cl(s) → NH₄⁺(aq) + Cl⁻(aq))

chemistry (1 decks)

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