How many atoms are in 15.9 g of Ag?

Number of silver atoms

=

0.0134

⋅

m

o

l

×

N

A

.  

N

A

=

Avogadro's number

Explanation:

Silver has a molar mass of  

107.87

g

⋅

m

o

l

−

1

.

What does this mean? It means that if I have such a mass of silver, there are Avogadro's number,  

N

A

=

6.022

×

10

23

,  

individual silver atoms.

So all I have to do is divide the mass by the molar mass, and multiply this number (a molar quantity!) by Avogadro's number.  

So, moles of silver  

=

1.45

⋅

g

107.87

⋅

g

⋅

m

o

l

−

1

=

0.0134

⋅

m

o

l

And  

number of silver atoms

=

0.0134

⋅

m

o

l

×

6.022

×

10

23

⋅

silver atoms  

m

o

l

−

1

=

?

?

silver atoms

Explanation:

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.