You are given a sample containing 0.40 moles of a . a) how many atoms are in the sample if the substance is copper? . b) how many atoms are in the sample if the substance is gold? . c) how many molecules are present in the sample if the substance is acetone, ch3coch3? .

a) 2.4 × 10²³ atoms Cu; b) 2.4 × 10²³ atoms Au; 2.4 × 10²³ molecules acetone

Explanation:

There are Avogadro’s number of particles in one mole of those particles.

a) Cu

Thus, 0.40 mol of any particles contains 2.4 × 10²³ of those particles.

b) 0.40 mol Au = 2.4 × 10²³ atoms Au

c) 0.40 mol acetone = 2.4 × 10²³ molecules acetone

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.