Answer:
Pencil is always used to mark chromatography paper or TLC plates because ink may run and interfere with the chromatogram. ... As soon as the paper/plate is taken out, mark the solvent front with a pencil before the solvent evaporates and the front becomes impossible to see.
Answer: 6.3 x 10^-3 moles
Explanation:
Based on Avogadro's law:
1 mole of any substance has 6.02 x 10^23 atoms
So, 1 mole of potassium = 6.02 x 10^23 atoms
Z moles = 3.78 x 10^21 atoms
To get the value of Z, we cross multiply:
(3.78 x 10^21 atoms x 1mole) = (6.02 x 10^23 atoms x Z moles)
3.78 x 10^21 = (6.02 x 10^23 x Z)
Z = (3.78 x 10^21) ➗ (6.02 x 10^23)
Z = 0.63 x 10^-2)
Place the result in standard form
Hence, Z = 6.3 x 10^-3 moles
Thus, there are 6.3 x 10^-3 moles of potassium in 3.78 x 10^21 atoms of K.
Answer:
2994 kJ
Explanation:
When one mol of ethane (C₂H₆) is combusted, 1451 kJ of heat is exchanged.
First we convert 61.9 g of C₂H₆ into moles, using its molar mass:
- 61.9 g ÷ 30 g/mol = 2.06 mol C₂H₆
Finally we <u>calculate how much heat is exchanged by the combustion of 2.06 moles of C₂H₆</u>:
- 2.06 mol * 1451 kJ/mol = 2994 kJ
Answer:
So yes! A mixture can contain just elements if those elements are not chemically reactive to one another. Air is a great example of an elemental mixture as it contains nitrogen, oxygen, and argon (along with some other compounds).
Explanation:
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