Advertisements
Advertisements
Question
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – copper carbonate.
Solution
Change of colour — In certain chemical reactions a change of colour is seen to be observed. Heat on substances to observe change in colour of reactants and products.
Heat on:
Copper carbonate CuCO3 → CuO + CO2[g]
Colour change:
Copper carbon [CuCO3] – Green – to Copper [III] oxide [CuO] – Black
APPEARS IN
RELATED QUESTIONS
Write the balanced chemical equation for the following reaction.
\[\ce{Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water}\]
What do you understand by endothermic reactions?
Balance the following equation. Also name the product formed.
N2 + H2 → NH3
Complete the following equation:
CH3COOH + NaOH →
What do the following symbol stand for?
2H2
Write the chemical equation for the following word equation and balance them.
Nitrogen + Oxygen → Nitrogen monoxide
Balance the following equation:
MnO2 + HCl → MnCl2 + H2O + Cl2
Considering the relationship in the first pair, complete the second paie :
AgCI : White :: CuI2 : ___________
Write a balanced equation for the following word equation:
Lead dioxide [lead (IV) oxide] → Lead monoxide + Oxygen
Three beakers labelled as A, B and C each containing 25 mL of water were taken. A small amount of NaOH, anhydrous CuSO4 and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is(are) correct?
- In beakers A and B, exothermic process has occurred.
- In beakers A and B, endothermic process has occurred.
- In beaker C exothermic process has occurred.
- In beaker C endothermic process has occurred.
