How many molecules are there in 840 grams of na2SO4

3.56x10^24 molecules

Explanation:

The following data were obtained from the question:

Mass of Na2SO4 = 840g

Molar Mass of Na2SO4 = (23 x2) + 32 + (16x4) =46 + 12 + 64 = 142g/mol

From Avogadro's hypothesis, 1mole of any substance contains 6.02x10^23 molecules. This also gives that 1mole of Na2SO4 contains 6.02x10^23 molecules.

If 1 mole (i.e 142g) contains 6.02x10^23 molecules,

Therefore, 840g of Na2SO4 will contain = (840 x 6.02x10^23)/142 = 3.56x10^24 molecules

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.