Chemistry 2006/ 2007 Club***

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I am starting Chem II this semester. Anyone want to start a club??? :rolleyes:

Specializes in LTC, subacute CNA.

I've got my first chemistry exam on Monday! I've been studying my butt off. *crosses fingers*

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Good luck on your test on Monday! I had my first test a week ago and made an 85. Because most of the class failed that test, the professor allowed a retest for a higher grade. He will take the higher of the 2 test scores. So I had the retest yesterday. I need that A so badly. Nursing school is getting so hard to get into down here!

Happy studying!

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I thought I had this all down pat, but now I'm confused about some homework problems. I am able to solve them (problem a was a *beast*) but not figure out the sig figs.

Also, when I am solving a problem with multiple steps, do I factor in the sig figs during the steps, or do I wait until the end? Example, I need 3 sig figs but in the first step of the problem my answer on the calculator has 8 figures. Do I carry those 8 figures over to the second part of the problem, or do I first round them to 3 sig figs? Either way will give me a slightly different final answer.:confused:

a) A sample of metal with a mass of 500.0 g is heated to 225.0 degrees C and then dropped into a 400.0 mL sample of water. The water's temperature is initially 24.0 degrees C and its final temperature (after the metal is dropped into it) is 36.0 degrees C. What is the specific heat of the metal in J/gC?

b) The amount of Vitamin C in an 8.000 fl oz. glass of orange juice is 0.5200 mg. How many liters of orange juice contain 25.0 g of Vitamin C? (1.0000 fluid oz = 29.573 ML measured)

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I thought I had this all down pat, but now I'm confused about some homework problems. I am able to solve them (problem a was a *beast*) but not figure out the sig figs.

Also, when I am solving a problem with multiple steps, do I factor in the sig figs during the steps, or do I wait until the end? Example, I need 3 sig figs but in the first step of the problem my answer on the calculator has 8 figures. Do I carry those 8 figures over to the second part of the problem, or do I first round them to 3 sig figs? Either way will give me a slightly different final answer.:confused:

a) A sample of metal with a mass of 500.0 g is heated to 225.0 degrees C and then dropped into a 400.0 mL sample of water. The water's temperature is initially 24.0 degrees C and its final temperature (after the metal is dropped into it) is 36.0 degrees C. What is the specific heat of the metal in J/gC?

b) The amount of Vitamin C in an 8.000 fl oz. glass of orange juice is 0.5200 mg. How many liters of orange juice contain 25.0 g of Vitamin C? (1.0000 fluid oz = 29.573 ML measured)

after the first unit my instructor doesn't worry about significant figures, but if I remember correctly we are suposed to do all the work first then figure significant figures. As far as your problems I will have to look them up it was 2 units ago we did joules and Specific heat lol I'll look though and see if I can figure it out.

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Specializes in LTC, subacute CNA.

Okay, I had my chem test a few days ago. It was my first real test in 6 years since my first round of college. I know for sure that I got one question wrong. A simple conversion and I can't figure out for the life of me how to get the right answer. Here it is:

d= 3.12g/mL. Convert it to kg/L. I kept getting 3.12kg/L.:confused: I tried solving the problem several different ways. It was like being in a bad dream! Anyone up to solving that one for me? I'm sure I am just missing something obvious.

Fortunately I did well on everything else. Or so I hope. I'll find out when I get the test back next week.

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Okay, I had my chem test a few days ago. It was my first real test in 6 years since my first round of college. I know for sure that I got one question wrong. A simple conversion and I can't figure out for the life of me how to get the right answer. Here it is:

d= 3.12g/mL. Convert it to kg/L. I kept getting 3.12kg/L.:confused: I tried solving the problem several different ways. It was like being in a bad dream! Anyone up to solving that one for me? I'm sure I am just missing something obvious.

Fortunately I did well on everything else. Or so I hope. I'll find out when I get the test back next week.

How many Kg in a gram?

How many liters in a ml? get your conversion factors and work the problem that way

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Hello all...My problem is that we are always step ahead in the lab then in the class (or two steps)...so I am stuck with some problems....They are similar to one (i bleieve) on this page but I just can not get it...

1. If 12 moles of Al2O3 are produced, how many moles of aluminum reacted?

2. If 75 g of oxygen react, how many grams of aluminum are required?

I belive i shoudl findmolar mass for Aj2O3 (101.96 g/mol) and i shoud do the ratio but I am not sure is that correct or not....Thanks all...

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In order to help you with this problem, we need to see the complete balance equation. What equation were these problems asked with?

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In order to help you with this problem, we need to see the complete balance equation. What equation were these problems asked with?

sorry;;;

4Al+3O2=2Al2O3

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ok, in the first problem I am getting the following:

4Al + 3O2 ----> 2Al2O3

1. If 12 moles of Al2O3 are produced, how many moles of aluminum reacted?

12 mol of Al2O3 X 4 mol Al/2mol Al203 = 24 mol Al

2. If 75 g of oxygen react, how many grams of aluminum are required?

In this problem you need to go from g O2 ---> mol O2 ---> mol Al --> g Al

75 g O2 x 1 mol O2/32.00 g O2 x 4 mol Al/3 mol O2 x 26.98 Al/1 mol Al = 84 g Al

Please someone double check me and I hope this helps.

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Specializes in LTC, subacute CNA.
How many Kg in a gram?

How many liters in a ml? get your conversion factors and work the problem that way

That's how I was doing the problem, and I still keep getting 3.12 kg/L as my answer. *scratches head*

3.12g * 1kg * 1000mL divided by

1mL 1000g 1L

=3.12kg/L

I also tried it as .001kg/g and .001mL/L

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ok, in the first problem I am getting the following:

4Al + 3O2 ----> 2Al2O3

1. If 12 moles of Al2O3 are produced, how many moles of aluminum reacted?

12 mol of Al2O3 X 4 mol Al/2mol Al203 = 24 mol Al

2. If 75 g of oxygen react, how many grams of aluminum are required?

In this problem you need to go from g O2 ---> mol O2 ---> mol Al --> g Al

75 g O2 x 1 mol O2/32.00 g O2 x 4 mol Al/3 mol O2 x 26.98 Al/1 mol Al = 84 g Al

Please someone double check me and I hope this helps.

Thank you...This make sence....It is so add to have Lab prior to class so we are doing lab before we acctualy learn it. Thanks again...

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