Answer:

Explanation:
We are asked to convert an amount in grams to moles. To do this, we use the molar mass. This is the number of grams in one mole of a substance. It is the same value numerically as the atomic mass on the Periodic Table, however the units are grams per mole, not atomic mass units.
Look up the molar masses for the individual elements.
- Sodium (Na): 22.9897693 g/mol
- Oxygen (O): 15.999 g/mol
Look back at the formula: Na₂O. Notice there is a subscript of 2 after sodium. This means there are 2 atoms of sodium in every molecule, so we have to multiply sodium's molar mass by 2 before adding oxygen's.
- Na₂O: 2(22.9897693 g/mol)+ 15.999 g/mol = 61.9785386 g/mol
Set up a ratio using the molar mass.

Multiply by the given number of grams.

Flip the ratio so the grams of sodium oxide can cancel each other out.




The original measurement of grams given has 3 significant figures, so our answer must have the same. For the number we calculated, that is the hundredth place.
The 4 in the thousandth place tells us to leave the 8.

There are <u>2.48 moles of sodium oxide</u> in 154 grams, so choice A is correct.
While bond energies and bond enthalpies can be used to estimate the heat of reaction (enthalpy change of a reaction), H, the heat of neutralization is the heat released when 1 mole of water is generated by the reaction of an acid and a base (reaction).
For the same type of bond, bond enthalpies differ from compound to compound. For instance, the C-H bond enthalpy in methane is nearly identical to that of ethane, butane, etc. When we look up the bond enthalpy for a C-H bond in a table of bond enthalpies, the average number that results may only be accurate to two or three significant figures.
Each compound's enthalpies of production are listed, and those numbers take into account any minor variations in the enthalpies of each bond. Therefore, the result will be more accurate if you utilize formation enthalpies rather than average bond enthalpies to compute a given reaction's enthalpy change.
Learn more about Bond enthalpy here-
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Answer:
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Explanation:
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Eight moles of O2 are found in 4 moles of H2O
Cl2O5+H20-->2HClO3
Just remember to have the same number of each element on both sides of the equation.