Answer:
Na2S
Explanation:Just took the test
Explanation:
Start with a balanced equation.
2H2 + O2 → 2H2O
Assuming that H2 is in excess, multiply the given moles H2O by the mole ratio between O2 and H2O in the balanced equation so that moles H2O cancel.
5 mol H2O × (1 mol O2/2 mol H2O) = 2.5 mol O2
Answer: 2.5 mol O2 are needed to make 5 mol H2O, assuming H2 is in excess.
<em>The statement that gives the relationship between energy needed in breaking a bond and the one that is released after breakin</em>g is
The amount of energy it takes to break a bond is always less than the amount of energy released when the bond is formed.
- Bond energy can be regarded as amount of energy that is required in breaking a particular bond.
- For a bond to be broken Energy will be added and when a bond is broken there will be release of energy
- Bond breaking can be regarded as endothermic process, it is regarded as endothermic because there is a lot of energy required to be absorbed.
- Where ever a bond is broken, there must be formation of another bond
- Bond forming on the other hand can be regarded as exothermic process, since there is a release of releases energy.
Therefore, more energy is required in breaking of bond compare to energy released after breaking of bond.
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Take mass of zinc divided by the relative molecular mass - 30 for zinc ( from periodic table)
