Answer:
No.
Explanation:
During chemical reaction, atomes cannot be created or destroyed, they can only react together to form <em>E</em><em>l</em><em>e</em><em>m</em><em>e</em><em>n</em><em>t</em><em> </em>or <em>C</em><em>o</em><em>m</em><em>p</em><em>o</em><em>u</em><em>n</em><em>d</em><em> </em>at the <em>P</em><em>r</em><em>o</em><em>d</em><em>u</em><em>c</em><em>t</em><em> </em>side.
Mass number of an element write in bottom of it!
So, there 80 would be the mass number of ₈₀Br.
Hope this helps!
15. 1 were lost
16. 3 were gained
17. 2 were lost
18. 1 was gained
You can figure that out by looking at the number nest to the molecule with a plus or minus sign next to it
+ = gained
- = lost
Answer:

Explanation:
<u>1. Convert Molecules to Moles</u>
First, we must convert molecules to moles using Avogadro's Number: 6.022*10²³. This tells us the number of particles in 1 mole of a substance. In this case, the particles are molecules of sodium hydroxide.

Multiply by the given number of molecules.

Flip the fraction so the molecules cancel out.




<u>2. Convert Moles to Grams</u>
Next, we convert moles to grams using the molar mass.
We must calculate the molar mass using the values on the Periodic Table. Look up each individual element.
- Na: 22.9897693 g/mol
- O: 15.999 g/mol
- H: 1.008 g/mol
Since the formula has no subscripts, we can simply add the molar masses.
- NaOH: 22.9897693+15.999+1.008=39.9967693 g/mol
Use this as a ratio.

Multiply by the number of moles we calculated.

The moles of sodium hydroxide cancel.



The original measurement of molecules has 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place. The 0 tells us to leave the 7 in the hundredth place.

1.20*10²² molecules of sodium hydroxide is approximately 0.797 grams.