Jen

OK, so I originally uninstalled my Dell Laser Printer 1500 because it started printing off symbols and numbers and would not print off anything else. I uninstalled everything that was possible. I then disconnected the printer and turned off the computer. I reconnected the printer and turned the computer back on, inserted the CD-ROM and plugged in the USB cord (as the directions said to). In order for the CD-ROM to work, the wizard must recognize the printer as new hardware. Well it is not recognizing it and I now cannot reinstall the disc. I am about ready to pull my hair out, so if anyone could help I would appreciate it.

Hello! I had to take an incomplete in my chemistry class last semester because my mom had 2 strokes. I am now reviewing old tests and quizes. There are some problems I have been unable to solve and would really really appreciate some help.

If you could please show me how to do this problem step by step.

Thanks!!

A syringe contains 589 mL of CO at 325K and 1.2 atm pressure. A second syringe containes 473 mL of N2 at 298K and 2.6 atm. What is the final pressure if the contents of these 2 syringes are injected into a 1.00 L container and STP?

Hello! I took an incomplete in my chemistry class last semester because my mom had 2 strokes. I now have to go back and make up my final exam. AHHH!! I am going over some old quizes and am trying to figure out the correct answers and how to do the problems. This problem has left me stumped. No wonder I got it wrong!

Please show me step by step how to do this problem. I have tried doing several things and cannot figure it out. Thank you so much!

A gas mixture consists of N2, O2, and Ne, where the mole fraction of N2 is 0.55 and the mole fraction of Ne is 0.25. If the mixture is at STP in a 5.0 L container, how many molecules of O2 are present?

Hello. I need some guidance as to how to complete this problem. Thanks in advance.

The binding energy of electrons in a metal is 186 kj/mol. Find the threshold frequency of the metal.

v=_________ s-1

Ok, I cannot figure this one out. Please tell me how to set it up and solve! Thanks!

Top fuel dragsters and funny cars burn nitromethane as fuel according to the following balanced combustion equation:

2 CH3NO2(l) + 3/2 O2(g) --> 2 CO2(g) + 3 H2O(g)

The standard enthalpy of combustion for nitromethane is -709.2 kJ/mol.

Calculate the standard enthalpy of formation for nitromethane. Answer in kJ/mol.

Thanks again

I am not sure how to cancel out some of the atoms in this equation. It almost appears that I should multiply the first equation by 2, after reversing. This would then give me 2 CaCo3, and I only need one. If someone could please explain how to complete this problem, or at least how to set it up correctly so everything cancels, I would appreciate it! Thanks!

Calculate the change in Hrxn for the following reaction:

CaO(s) + CO2(g) --> CaCO3(s)

Use the following reactions and H values:

Ca(s) + CO2(g) 1/2O2(g) --> CaCO3(s) Change H= -812.8 kJ

2Ca(s) + O2(g) --> 2CaO(s) Change H= -1269.8 kJ

Express answer in kJ using 4 sig figs.

THANKS!

Use the following reactions and given .

ok, I know the answer which is supposed to be 29.3, but I am getting 27.0. Please help explain...

The molar heat capacity of silver is 25.35 J/mol*C. How much energy would it take to raise the temperature of 8.80 g of silver by 14.2 degrres Celsius?

Wouldn't I figure out how many moles of silver, then multiply all 2 together? It comes out to be 27... Hmm...

A 0.2861 gram sample of an unknown acid (HX) required 32.63 mL of 0.1045 M NaOH for neutralization to a phenolphthalein endpoint. What is the molar mass of the acid?

I figured out that there was 0.003409835 moles of NaOH. Would I then take and divide the grams of the unknown acid by this number? It would give me 83.90 for the molar mass? I am confused! Thanks for the help!

Hard water often contains dissolved Ca^{2 + } and Mg^{2 + } ions. One way to soften water is to add phosphates. The phosphate ion forms insoluble precipitates with calcium and magnesium ions, removing them from solution. Suppose that a solution is 5.5×10−2 M in calcium chloride and 9.5×10−2 M in magnesium nitrate.

What mass of sodium phosphate would have to be added to 2.0 L of this solution to completely eliminate the hard water ions? Assume complete reaction.

Ok, this question is similar to what I have already asked, but I really need help! I am finishing up a lab report.. Here is the quesiton:

Use your measured conductances for 0.025 M KCl, HCl, abd HNO3 to predict the conductance of a solution of 0.025 M KNO3. Compare this prediction to your measured value?

KCl = 3.5 mS

HCl = 10.60 mS

HNO3 = 11.09 mS

Actual results of KNO3 = 3.60 mS

Thanks!

Ok, I am trying to finish up a lab report but have come to a point where I am stuck. We measured the conductivities of several solutions and I am now answering post lab questions. The question is as follows:

Use your measured conductances for 0.025 M KCl and 0.025 M KNO3 to predict which of the following solutions will have the larger conductance: 0.1 M NaCl or 0.1 M NaNO3, and explain how you arrived at your prediction.

RESULTS: KCl = 3.5 mS

KNO3 = 3.6 mS

Would they be the same? Please explain and help me out!!

One other quick question while I have your attention, if an ion has a higher charge, does it have a higher conductivity? Thanks!!

Ok, I am just not understanding all of this, so any help would be appreciated!!

For part of the experiment, you will need to prepare 100 mL of 0.025 M CH3CO2H, starting from commercial "glacial" acetic acid, which has a concentration of 17.4 M. This is best done by making two dilutions, in order to avoid either having to measure out an extremely small volume of glacial acetic acid, or having to make a very large volume of diluted acid. For example, you could measure out 1.00 mL of glacial acetic acid, dilute it to 50.00 mL in a 50 mL volumetric flask, and then take 7.2 mL of this solution, and it dilute it to 100.00 mL in a 100 mL volumetric flask.

Verify this procedure will result in 100 mL of 0.025 M acetic acid.

SECOND PART:

Devise a method similar to that in the previous question to make 100.00 mL of 0.025 M NH3, from concentrated ammonia, which has a concentration of 14.5 M?

I know this is long, but I stumped as to how to even do this... Thanks to everyone who helps!!!

Ok, I am just not understanding all of this, so any help would be appreciated!!

For part of the experiment, you will need to prepare 100 mL of 0.025 M CH3CO2H, starting from commercial "glacial" acetic acid, which has a concentration of 17.4 M. This is best done by making two dilutions, in order to avoid either having to measure out an extremely small volume of glacial acetic acid, or having to make a very large volume of diluted acid. For example, you could measure out 1.00 mL of glacial acetic acid, dilute it to 50.00 mL in a 50 mL volumetric flask, and then take 7.2 mL of this solution, and it dilute it to 100.00 mL in a 100 mL volumetric flask.

Verify this procedure will result in 100 mL of 0.025 M acetic acid.

SECOND PART:

Devise a method similar to that in the previous question to make 100.00 mL of 0.025 M NH3, from concentrated ammonia, which has a concentration of 14.5 M?

I know this is long, but I stumped as to how to even do this... Thanks to everyone who helps!!!

ok, mostly I would just like someone who knows what they are doing to tell me if this would be correct...

0.0125/0.025= 0.5 L = 500mL Would I then divide by 100, since I am only going to have 100mL? I would then add 5 mL of the solution and fill up the flask to the 100mL point?

Ok, I am working on a lab report and this one equation is not making very much sense... I need to know the net ionic equation for:

Zn(s) + H2SO4(l)  ZnSO4(aq) + H2(g)

I am getting Zn --> Zn(2+)

I know that something has to be oxidized for this to be reduced.. Is my equation wrong? Or is this correct? Thanks :o)

I am not sure how to approach this problem... Any help would be great!

An acid solution is 0.100 M in HCl and 0.210 M in H2SO4.

What volume of a 0.160 M KOH solution would have to be added to 550.0 mL of the acidic solution to neutralize completely all of the acid?

In a student experiment, the empirical formula of a copper halide was found by adding aluminum metal to an aqueous solution of the halide, displacing copper metal. The copper metal was filtered, washed with distilled water, dried, and weighed; three separate determinations were performed. The copper halide solution contained 42.62 \rm g of copper chloride per liter. The student recorded the following experimental data.

Trial, Volume of copper chloride solution, Mass of filter paper, Mass of filter paper plus copper

A - 49.6- 0.908 - 1.694

B - 48.3- 0.922 - 1.693

C - 42.2 - 0.919 - 1.588

Write the empirical formula of copper chloride based on the experimental data.

Ok, I have been working on this problem and I keep getting confused. If someone could show me step by step, it would be very much appreciated!!!

A particular coal contains 2.55% sulfur by mass. When the coal is burned, it produces SO2 emissions which combine with rainwater to produce sulfuric acid.

Determine how much sulfuric acid (in metric tons) is produced by the combustion of 1.2 metric ton of this coal. (A metric ton is 1000 kg).

Do you think I would use the 2.55 % as 1 coal produces 2.55 grams?

not sure if it matters but the question before this, was how much S is in Sulfuric Acid and the answer is 32.7%. This is correct...

In a student experiment, the empirical formula of a copper halide was found by adding aluminum metal to an aqueous solution of the halide, displacing copper metal. The copper metal was filtered, washed with distilled water, dried, and weighed; three separate determinations were performed. The copper halide solution contained 42.62 \rm g of copper chloride per liter. The student recorded the following experimental data.

Trial, Volume of copper chloride solution, Mass of filter paper, Mass of filter paper plus copper

A - 49.6- 0.908 - 1.694

B - 48.3- 0.922 - 1.693

C - 42.2 - 0.919 - 1.588

Write the empirical formula of copper chloride based on the experimental data.

Ok, I have been working on this problem and I keep getting confused. If someone could show me step by step, it would be very much appreciated!!!

A particular coal contains 2.55% sulfur by mass. When the coal is burned, it produces SO2 emissions which combine with rainwater to produce sulfuric acid.

Determine how much sulfuric acid (in metric tons) is produced by the combustion of 1.2 metric ton of this coal. (A metric ton is 1000 kg).

Do you think I would use the 2.55 % as 1 coal produces 2.55 grams? I cannot figure out how to line this up. Thanks in advance! You guys are awesome!!!