On the basis of the given unbalanced equation, that is:
HBr (aq) + 2NaOH (aq) → 2NaBr (s) + H2O (l)
On the right side of the equation, there are 2 atoms of sodium (Na), 2 atoms of bromine (Br), 2 atoms of hydrogen (H), and 1 atom of oxygen (O₂).
After balancing the equation correctly we get:
HBr (aq) + NaOH (aq) → NaBr (s) + H2O (l)
On the right side, one atom of Na, 1 atom of Br, 1 atom of H and one atom of O₂.
Acids will typically start with a Hydrogen, so HI and HNO₃ are most likely
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.
The number of grams of NaOH that are needed to make 500 ml of 2.5 M NaOH solution
calculate the number of moles =molarity x volume/1000
= 2.5 x 500/1000 = 1.25 moles
mass = moles x molar mass of NaOH
= 1.25 x40= 50 grams of NaOH
Answer:
At STP one mole of any gas occupies a volume of 22.4 L: this is the molar volume.
Explanation: