The reactivity series: compare reactions at room temperature
| English | Português |
|---|---|
| reactivity series/rɪəkˈtɪvɪti ˈsɪəriːz/ | reactivity series |
| positive ion | positive ion |
What would explain this observation?
- Copper does not release hydrogen from dilute hydrochloric acid, while magnesium reacts readily. The contrast helps locate them relative to hydrogen in the reactivity series 金属活动性顺序.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- For the specified metals, descending reactivity is potassium, sodium, lithium, calcium, magnesium, zinc, iron, copper. Include carbon above zinc and hydrogen below iron when using extraction or acid rules; aluminium is commonly shown above carbon in the fuller series. More reactive metals more readily form positive ions · íons positivos 正离子. In this section comparisons are at room temperature, not reactions with steam.
- reactivity series: An ordering of metals by their tendency to react and form positive ions; positive ion: A particle with a net positive electrical charge.
Which listed metal does not release hydrogen from dilute hydrochloric acid under the stated conditions?
Potassium, sodium and lithium react vigorously with cold water to produce hydroxides and hydrogen, with potassium generally most vigorous. Calcium also reacts, producing hydrogen and calcium hydroxide. Magnesium reacts very slowly with cold water, while zinc, iron and copper show no appreciable reaction under this school comparison. With dilute hydrochloric or sulfuric acid, Mg, Zn and Fe produce hydrogen, with Mg more vigorous and Fe slower; Cu does not. Very reactive alkali metals are not student acid-test samples.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Potassium, sodium and lithium react vigorously with cold water to produce hydroxides and hydrogen, with potassium generally most vigorous. Calcium also reacts, producing hydrogen and calcium hydroxide. Magnesium reacts very slowly with cold water, while zinc, iron and copper show no appreciable reaction under this school comparison. With dilute hydrochloric or sulfuric acid, Mg, Zn and Fe produce hydrogen, with Mg more vigorous and Fe slower; Cu does not. Very reactive alkali metals are not student acid-test samples.
- Compare suitable teacher-approved metal samples under controlled acid concentration, volume, temperature and exposed surface conditions. Observe bubbles and metal consumption, but do not treat raw bubble counts from different-sized samples as a pure reactivity measure. Use supplied evidence or a teacher demonstration for highly reactive metals. Steam reactions and detailed unusual conditions are outside this stated recall scope.
Which two habits make the investigation or model in this case more defensible?
Compare suitable teacher-approved metal samples under controlled acid concentration, volume, temperature and exposed surface conditions. Observe bubbles and metal consumption, but do not treat raw bubble counts from different-sized samples as a pure reactivity measure. Use supplied evidence or a teacher demonstration for highly reactive metals. Steam reactions and detailed unusual conditions are outside this stated recall scope.
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: supplied observations show metal A reacts with cold water; B does not appreciably react with water but releases hydrogen in dilute acid; C does neither. Under comparable conditions, A>B>C is supported. A separate acid test collects 36 cm³ gas in 60 s, giving mean collection rate 0.60 $\dfrac{\text{cm}^3}{\text{s}}$; this is method-specific evidence, not a universal rate constant.
A supervised model test collects 48 cm³ gas in 80 s. Find mean collection rate. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A supervised model test collects 48 cm³ gas in 80 s. Find mean collection rate.
The result is 0.6 cm³ per s. Known: supplied observations show metal A reacts with cold water; B does not appreciably react with water but releases hydrogen in dilute acid; C does neither. Under comparable conditions, A>B>C is supported. A separate acid test collects 36 cm³ gas in 60 s, giving mean collection rate 0.60 cm³ per second; this is method-specific evidence, not a universal rate constant.
Check the conclusion and its limits
- No visible reaction does not mean a substance can never react under any condition. A protective layer or unequal surface area can affect observations. Hydrogen and carbon are comparison positions, not metals. Do not mix the source’s room-temperature scope with magnesium-steam reactions.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
All listed metals react equally with cold water at room temperature. This claim is false: No visible reaction does not mean a substance can never react under any condition. A protective layer or unequal surface area can affect observations. Hydrogen and carbon are comparison positions, not metals. Do not mix the source’s room-temperature scope with magnesium-steam reactions.
The reactivity series: compare reactions at room temperature: Potassium, sodium and lithium react vigorously with cold water to produce hydroxides and hydrogen, with potassium generally most vigorous. Calcium also reacts, producing hydrogen and calcium hydroxide. Magnesium reacts very slowly with cold water, while zinc, iron and copper show no appreciable reaction under this school comparison. With dilute hydrochloric or sulfuric acid, Mg, Zn and Fe produce hydrogen, with Mg more vigorous and Fe slower; Cu does not. Very reactive alkali metals are not student acid-test samples.
All listed metals react equally with cold water at room temperature.
No visible reaction does not mean a substance can never react under any condition. A protective layer or unequal surface area can affect observations. Hydrogen and carbon are comparison positions, not metals. Do not mix the source’s room-temperature scope with magnesium-steam reactions.
An ordering of metals by their tendency to react and form positive ions: write the technical term.
reactivity series means An ordering of metals by their tendency to react and form positive ions.