Someone me: balance the following reaction: a2b + dc3 --> ac + d2b3 hint: don't do this in your head. use a piece of paper and a pencil. when this reaction is balanced, what number must be to the left of ac?(use numerals such as 1, 2, or 3; not words such as one, two, or three)

The number to the left of AC should be 6.

Explanation: The balanced chemical reaction is one in which the number of atoms  of each element on the reactant side must be equal to the number of atoms on product side.

The given equation is unbalanced as the atoms on the reactant side are not same as number of  atoms on product side. This equation is called as skeletal equation.

The balanced chemical equation is :

Thus the number to the left of AC is 6.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.