Neutralisation: select products and balance salt charges
도입됨| English | 의미 |
|---|---|
| alkali/ˈælkəlaɪ/ | 가용성 염기 |
| base/beɪs/ | 염기성 물질 |
What would explain this observation?
- Copper oxide with sulfuric acid gives copper sulfate and water. Changing the acid to nitric acid changes the salt’s negative ion, even though copper stays the positive ion.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Acid plus a metal oxide or hydroxide gives salt and water. Acid plus a metal carbonate gives salt, water and carbon dioxide. An alkali 可溶性碱 is a soluble base 碱性物质; some bases are insoluble. Hydrochloric acid supplies chloride salts, nitric acid nitrate salts and sulfuric acid sulfate salts. The base, alkali or carbonate supplies the positive ion.
- base: A substance that neutralises an acid; it need not be soluble; alkali: A soluble base producing hydroxide ions in aqueous solution.
Which products form when calcium carbonate reacts with hydrochloric acid?
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
Carbonate plus acid gives the salt, water AND carbon dioxide; the acid is hydrochloric, so the salt is calcium chloride. Sulfate needs sulfuric acid, and carbonates release carbon dioxide, never oxygen.
Match each technical term to its precise meaning.
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Use charges to make a neutral formula: Cu²⁺ and SO₄²⁻ give CuSO₄; Mg²⁺ and NO₃⁻ give Mg(NO₃)₂. CuO + H₂SO₄ → CuSO₄ + H₂O is balanced. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ has two chloride ions per calcium ion and one carbon dioxide molecule per carbonate formula unit.
- Identify the acid first, then the positive ion and required ratio. Use brackets when more than one polyatomic ion is needed, keeping the nitrate or sulfate group intact. Confirm atom counts in the full equation. Observe carbon dioxide with the approved limewater test where appropriate, rather than treating all bubbles as hydrogen.
Which two habits make the investigation or model in this case more defensible?
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: aluminium ions Al³⁺ combine with sulfate SO₄²⁻. Two aluminium ions supply +6 and three sulfates supply −6, giving Al₂(SO₄)₃. The formula contains two Al, three S and twelve O atoms. This formula exercise uses supplied ions and does not require conducting a reaction with aluminium oxide in class.
How many nitrate ions NO₃⁻ balance the charge of four Mg²⁺ ions? Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
How many nitrate ions NO₃⁻ balance the charge of four Mg²⁺ ions?
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
The result is 8 ions. Known: four Mg2+ ions carry total charge +8. Each nitrate NO3- carries -1, so 8 nitrate ions balance them. This is the same reasoning that writes Mg(NO3)2.
Check the conclusion and its limits
- Water is a product of oxide/hydroxide neutralisation, while carbonate neutralisation also produces carbon dioxide. A base need not dissolve in water to react with acid. A salt’s name depends on both ions, and the polyatomic-ion subscript inside its own formula must not be altered to balance charge.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Every base must dissolve in water to neutralise an acid. This claim is false: A base is a metal oxide, hydroxide or carbonate whether or not it dissolves. Insoluble copper oxide neutralises acid perfectly well; an ALKALI is the special case of a base that does dissolve.
Neutralisation: select products and balance salt charges: Use charges to make a neutral formula: Cu²⁺ and SO₄²⁻ give CuSO₄; Mg²⁺ and NO₃⁻ give Mg(NO₃)₂. CuO + H₂SO₄ → CuSO₄ + H₂O is balanced. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ has two chloride ions per calcium ion and one carbon dioxide molecule per carbonate formula unit.
Every base must dissolve in water to neutralise an acid.
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
A base is a metal oxide, hydroxide or carbonate whether or not it dissolves. Insoluble copper oxide neutralises acid perfectly well; an ALKALI is the special case of a base that does dissolve.
A substance that neutralises an acid; it need not be soluble: write the technical term.
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
base means A substance that neutralises an acid; it need not be soluble.