Answer:
21
Explanation:
Let us count the number of individual atoms for Na2S2O3 (the compound name):
Na: 2
S: 2
O: 3
This brings us to a total of 7 atoms for one molecule of sodium thiosulfate. For three of these compounds, we get 3*7=21
The cubes have only the same volume, so the answer is c.
Answer:
A
Explanation:
Recall that a mole of any substance contains 6.02 × 10²³ amounts of that substance.
In other words, a mole of gold atoms contains 6.02 × 10²³ gold atoms.
Hence, by dimensional analysis, we have that:
Therefore, there is about 7.99 × 10⁻³ moles of gold present in the sample.
In conclusion, the answer is A.
Answer:
The final volume is 6.4 L.
Explanation:
Dilution is reducing the concentration of a chemical and is achieved by adding more solvent to the same amount of solute. In other words, dilution is the procedure that is followed to prepare a less concentrated solution from a more concentrated one, and it simply consists of adding more solvent.
In a dilution the amount of solute does not vary, and as only more volume (and mass) of solvent is being added, the concentration of the solute decreases.
In a dilution the expression is used:
Ci*Vi = Cf*Vf
where:
- Ci: initial concentration
- Vi: initial volume
- Cf: final concentration
- Vf: final volume
In this case:
- Ci: 8 M
- Vi: 2 L
- Cf: 2.5 M
- Vf: ?
Replacing:
8 M* 2 L= 2.5 M* Vf
Solving:
Vf=6.4 L
<u><em>The final volume is 6.4 L.</em></u>