Question

For each reaction write a balanced chemical equation and then below the chemical formula of each reactant and product write a brief description of the substance (color and cal state). Also, indicate whether the reaction is exothermic, endothermic, or cannot tell.

Answer 1

3.

Cu + 2 AgNO3 $\small \to$ 2 Ag + Cu(NO3)

it is a displacement reaction , this type of reaction is exothermic.

Evidence of chemical change : the solution becomes blue.

4.

CaCl2 + Na2CO3 $\small \to$ CaCO3 + 2 NaCl

it is a precipitation reaction , it can be $\small \to$   or exothermic . So correct choice is Cannot tell

Evidence of chemical change ; Formation of white precipitate of CaCO3 .

5.

CaCO3 + 2 HCl $\small \to$ CaCl2 + H2O+ CO2

It is an exothermic reaction .

Evidence of chemical change ; Formation of effervescence of carbon dioxide .

6.

This is a chemical change , silver ion is reduced by some solid Zn .

Ag+ + Zn + ZnCl2 $\small \to$   Ag + Zn + ZnCl2

It is a displcement reaction , hence exothermic .

Evidence of chemical change ; Color change of penny from red to silver .