| molarity questions need help with by tommorow!!! |
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g-funk
Probably not a bot. Junior Member.
Joined: 09 May 2005
Posts: 3
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 Posted: Fri May 20, 2005 3:09 am Post subject: molarity questions need help with by tommorow!!! |
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i ma having difficulty wiht these questions i got an answer of b for the first one and got 6.24 for the second one and the thirty one is a mystery in help would be much appreciated...
#558 of Molarities
A solution was prepared by mixing 35.0 mL of 0.200 M NaF with 28.5 mL of 0.350 M NaF. Assuming that the volumes are additive, what is the molarity of NaF in the final solution?
a. 0.275 M NaF
b. 0.280 M NaF
c. 0.270 M NaF
d. 0.276 M NaF
e. 0.267 M NaF
Save answer
Question 12 (1.0 points)
Arrhenius
A second order reaction has rate constant 2.32 x 107 L/mol/s at 79°C, and 2.74x 106 at -38°C. What is the activation energy of this reaction in J/mol?
( Do not use scientific notation or put in units but give your answer to 4 significant figures eg 3.214 x 103 in the form eg 3.214e3)
Answer:
Question 13 (1.0 points)
Electrolysis
Chromium metal can be electroplated from an acidic solution of CrO3. How many seconds will it take to plate 1.47 gram of chromium using a current of 6.54 A?
Answer to 4 significant figures and do not use scientific notation or write in units.
Answer:
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Borek
Regular
Joined: 03 May 2005
Posts: 39
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| Posted: Fri May 20, 2005 10:23 pm Post subject: Re: molarity questions need help with by tommorow!!! |
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| g-funk wrote: |
| A solution was prepared by mixing 35.0 mL of 0.200 M NaF with 28.5 mL of 0.350 M NaF. Assuming that the volumes are additive, what is the molarity of NaF in the final solution? |
Try CASC and solution mixer.
http://www.chembuddy.com/?left=CASC&right=solution_dilution
Best,
Borek
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GCT
Member
Joined: 21 May 2005
Posts: 12
Location: Georgia
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| Posted: Sat May 21, 2005 10:03 pm Post subject: Re: molarity questions need help with by tommorow!!! |
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greetings
| g-funk wrote: |
i ma having difficulty wiht these questions i got an answer of b for the first one and got 6.24 for the second one and the thirty one is a mystery in help would be much appreciated...
#558 of Molarities
A solution was prepared by mixing 35.0 mL of 0.200 M NaF with 28.5 mL of 0.350 M NaF. Assuming that the volumes are additive, what is the molarity of NaF in the final solution?
a. 0.275 M NaF
b. 0.280 M NaF
c. 0.270 M NaF
d. 0.276 M NaF
e. 0.267 M NaF
Save answer
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Why don't you try it out first? hint: M1V1=M2V2. Or you can deduce the moles of each solution, count this as the total mole, and then divide by the total volume.
| Quote: |
Question 12 (1.0 points)
Arrhenius
A second order reaction has rate constant 2.32 x 107 L/mol/s at 79°C, and 2.74x 106 at -38°C. What is the activation energy of this reaction in J/mol?
( Do not use scientific notation or put in units but give your answer to 4 significant figures eg 3.214 x 103 in the form eg 3.214e3)
Answer: |
Try graphing the result in relevance to the Arrehnius equation. You can show us some work in discussing the problem in respect to the equation, which would include posting the equation itself for all of us to see.
[/quote]
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Question 13 (1.0 points)
Electrolysis
Chromium metal can be electroplated from an acidic solution of CrO3. How many seconds will it take to plate 1.47 gram of chromium using a current of 6.54 A?
Answer to 4 significant figures and do not use scientific notation or write in units.
Answer: |
First, you'll need to write out the overall redox reaction, find the relationship (moles of Cr (s) with respect to moles of electrons), that is the stoichiometric ratio.
Using this relationship, and deducing the moles of chromium from the gram value provided, you can deduce the total charge value in terms of columbs.
and remember I=C/s
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