<span>Avogadro's number
represents the number of units in one mole of any substance. This has the value
of 6.022 x 10^23 units / mole. This number can be used to convert the number of
atoms or molecules into number of moles.
163 g Ca (1 mol / 40.08 g) ( </span>6.022 x 10^23 atoms / 1 mol ) = 2.45 x10^24 atoms Ca
Answer:
The energy released as heat when 9.94 g Cu 2 O ( s ) undergo oxidation at constant pressure is -10.142 kJ
Explanation:
Here we have
2Cu₂O ( s ) + O₂ ( g ) ⟶ 4 CuO ( s ) Δ H ∘ rxn = − 292.0 kJ mol
In the above reaction, 2 Moles of Cu₂O (copper (I) oxide) react with one mole of O₂ to produce 4 moles of CuO, with the release of − 292.0 kJ/mol of energy
Therefore,
1 Moles of Cu₂O (copper (I) oxide) react with 0.5 mole of O₂ to produce 2 moles of CuO, with the release of − 146.0 kJ of energy
We have 9.94 g of Cu₂O with molar mass given as 143.09 g/mol
Hence the number of moles in 9.94 g of Cu₂O is given as
9.94/143.09 = 6.95 × 10⁻² moles of Cu₂O
6.95 × 10⁻² moles of Cu₂O will therefore produce 6.95 × 10⁻² × − 146.0 kJ mol or -10.142 kJ.
<span>Mass is a property that determines how much effort it takes to change somethings velocity. Weight is how much downward force does something exert in a gravitational field which is just the amount of gravity time the mass of an object. We use mass interchangeable with weight because everything on earth experiences the same amount of gravity or close to it, and so something that weighs twice as much as something else also has twice as much mass as that something else. Weight can actually vary for the same mass here on earth the strength of gravity changes from one place to another by small amounts, not enough to ruin your cooking recipe instructions, and weight can change dramatically for something that is falling, the strength of gravity for astronauts in orbit is not much reduced in comparison to here on earth, if there was no gravity they wouldn't go around the earth, they are weightless because they are falling and have enough sideways velocity to keep missing the earth, but their mass has not changed, it still requires effort to get them moving or to stop them.
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