A0.784 g sample of magnesium is added to a 250 ml flask and dissolved in 150ml of water. magnesium hydroxide obtained from the reaction required 215.0 ml of 0.300 m hydrochloric acid to completely react. how many moles of mg were used?

The chemical reaction involving Mg(OH)2 and HCl is:

Mg(OH)2  +  2HCl  -->  MgCl2  +  2H2O

So we see that for every 2 moles of HCl, 1 mole of Mg is reacted.

Calculating for moles HCl:

moles HCl = 0.300 M * 0.215 L

moles HCl = 0.0645 mol

The moles Mg then is:

moles Mg = 0.0645 mol * (1 / 2)

moles Mg = 0.03225 mol

0.03255 moles of Mg is used for neutralizing 0.3 M 245 ml .

The chemical reaction of the reaction of Mg with water yields Magnesium hydroxide.

The neutralization reaction of with HCl will be:

For neutralizing 1 mole of magnesium hydroxide 2 moles of HCl are required.

The moles  of HCl in the question are:

moles =

moles of HCl = 0.3

moles of HCl = 0.0645 moles.

The moles of Mg required are half of HCl.

Moles of Mg =

Moles of Mg = 0.03225.

0.03255 moles of Mg is used for neutralizing 0.3 M 245 ml .

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a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.

increased stability in the completion of fluorine's outer shell.