Answer:

Explanation:
We are asked to find how many moles of sodium carbonate are in 57.3 grams of the substance.
Carbonate is CO₃ and has an oxidation number of -2. Sodium is Na and has an oxidation number of +1. There must be 2 moles of sodium so the charge of the sodium balances the charge of the carbonate. The formula is Na₂CO₃.
We will convert grams to moles using the molar mass or the mass of 1 mole of a substance. They are found on the Periodic Table as the atomic masses, but the units are grams per mole instead of atomic mass units. Look up the molar masses of the individual elements.
- Na: 22.9897693 g/mol
- C: 12.011 g/mol
- O: 15.999 g/mol
Remember the formula contains subscripts. There are multiple moles of some elements in 1 mole of the compound. We multiply the element's molar mass by the subscript after it, then add everything together.
- Na₂ = 22.9897693 * 2= 45.9795386 g/mol
- O₃ = 15.999 * 3= 47.997 g/mol
- Na₂CO₃= 45.9795386 + 12.011 + 47.997 =105.9875386 g/mol
We will convert using dimensional analysis. Set up a ratio using the molar mass.

We are converting 57.3 grams to moles, so we multiply by this value.

Flip the ratio so the units of grams of sodium carbonate cancel.




The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we found that is the thousandth place. The 6 in the ten-thousandth place to the right tells us to round the 0 up to a 1.

There are approximately <u>0.541 moles of sodium carbonate</u> in 57.3 grams.
CO2 goes on the bottom and O2 on the top.
Answer:
Well, not always. It depends on where you're doing the boiling. In fact, water will boil at about 202 degrees in Denver, due to the lower air pressure at such high elevations
Explanation:
The difference in the reactivity of metals accounts for why some metals will react with hot water but not with cold water. For example, aluminum is less reactive than sodium and will only react with hot water but not cold water.
<h3>What is reactivity of metals?</h3>
The reactivity of metals is the ability of a metals to lose electrons.
The reactivity of metals generally decreases from left to right across the periodic table but increases on going down a group.
Due to the differences in reactivity of metals, some metals are more reactive than others.
For example, the reactive metals sodium, potassium and calcium react with cold water to with differing degree of spontaneity to liberate hydrogen.
Some other metal like aluminum, zinc, and iron can only react with hot water or steam to liberate hydrogen.
Therefore, the reactivity of a metal will determine if it will react with cold water or hot water.
Learn more about reactivity of metals at: brainly.com/question/28107797
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