A student adds hydrochloric acid to sodium hydrogen carbonate. Which observation confirms neutralization?
Effervescence
Hydrochloric acid (HCl) is an acid and sodium hydrogen carbonate (NaHCO3) is a mild base. When they meet they react as HCl + NaHCO3 → NaCl + H2O + CO2, and the carbon dioxide gas that is released escapes as bubbles, which is seen as effervescence.
Neutralisation of an acid and a base is exothermic, so the temperature usually rises slightly — it does not drop. NaCl is highly soluble in water, so no precipitate forms. Colour change to red would need an acid-base indicator like methyl orange or litmus, which is not being used here. Therefore, the visible bubbling of CO2 is the observation that confirms the reaction.
Hence, the answer is Effervescence.
Similar Questions
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Balance the following reaction:
\(3\,\text{MnO}_2\,(s) + x\,\text{Al}\,(s) \rightarrow 3\,\text{Mn}\,(l) + y\,\text{Al}_2\text{O}_3\,(s) + \text{Heat}\)
What type of ions exchange between reactants in a double displacement reaction?
A student tries to balance the equation Fe + H2O → Fe3O4 + H2 and writes the following step:
Fe + H2O4 → Fe3O4 + H2
Which statement best explains why this step is INCORRECT?
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Identify the correct statement regarding the reaction of sodium carbonate and dilute HCl.
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When carbon dioxide gas is passed through lime water (calcium hydroxide solution), it produces a white precipitate which is of:
Read the following statements and choose the correct option.
Statement I: All metals in the reactivity series can displace hydrogen from dilute acids to form hydrogen gas.
Statement II: Metals below hydrogen in the reactivity series do not produce hydrogen gas with dilute acids.
Important Questions from Chemical Reaction
Which of the following statement is/are true?
I. In physical change new substance is formed. substance is formed.
II. In chemical change no new substance is formed.
Which of the following cells involves similar chemical reactions?
The information not obtained from balanced chemical equation is
Oxygen cannot be obtained by which one of the following methods?
Which of the following statement is correct?
I. Insoluble salt is obtained by precipitation reaction.
II. Addition of oxygen or loss of hydrogen is called oxidation.
