Question M19 (Molecular Formula)
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Question M19 (Molecular Formula)
For question M19, I'm very confused as to how to find the amount of grams of oxygen in the compound caffeine, because 2 of the products (CO2 and H20) both have oxygen! Please help
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Re: Question M19 (Molecular Formula)
What I did is I found out how many grams of carbon (0.682g * (1 mol CO2/44.01g) * (1 mol C/1 mol CO2) * molar mass of carbon to get grams), hydrogen (same process as carbon), and nitrogen. Then I did 0.376-(mass carbon+mass hydrogen+mass nitrogen) to get the grams of oxygen, and then divided that by the molar mass to get the moles of oxygen. Hopefully this helps!
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- Posts: 54
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Re: Question M19 (Molecular Formula)
What also helps to remember is that typically for combustion reactions, for every 1 mole of CO2 produced, 1 mole of C was in the initial compound; for every 1 mole of H2O produced, 2 moles of H were in the initial compound; and for every 1 mole of N2 produced, 2 moles of N were in the initial compound. After identifying the moles of CO2, H2O, and N2 (using the given masses), you can then identify how many moles were present for each of the individual C, H, and N atoms.
Re: Question M19 (Molecular Formula)
Justin Chang 1K wrote:What I did is I found out how many grams of carbon (0.682g * (1 mol CO2/44.01g) * (1 mol C/1 mol CO2) * molar mass of carbon to get grams), hydrogen (same process as carbon), and nitrogen. Then I did 0.376-(mass carbon+mass hydrogen+mass nitrogen) to get the grams of oxygen, and then divided that by the molar mass to get the moles of oxygen. Hopefully this helps!
It did help, thank you so much!
Re: Question M19 (Molecular Formula)
Ava Harvey 1B wrote:What also helps to remember is that typically for combustion reactions, for every 1 mole of CO2 produced, 1 mole of C was in the initial compound; for every 1 mole of H2O produced, 2 moles of H were in the initial compound; and for every 1 mole of N2 produced, 2 moles of N were in the initial compound. After identifying the moles of CO2, H2O, and N2 (using the given masses), you can then identify how many moles were present for each of the individual C, H, and N atoms.
Awesome, thank you so much!
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Re: Question M19 (Molecular Formula)
Also, its important to remember that oxygen is typically a reactant in combustion reactions. Remember to include this in your equation.
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