# Posts by Lyndsay

Total # Posts: 37

**Chemistry**

A dye has a ?max = 460 nm (? = 70,000 L/(mol*cm)). What is the concentration of dye in a sample whose absorbance at 460 nm is A = 0.350 in a cell with a path length of 1.00 cm (4 points) I have no idea how to do this.

**Chemistry help!!**

Calculate the concentration of a solution prepared by adding 15.00 mL of 2.10 X 10^-3 M KMnO4 from a buret into a 50.00 mL volumetric flask, which is then filled to the 50.00 mL graduation mark with distilled water.

**Chemistry help!!**

I figured that out but I need help with this one: How many moles of P4 would be required to produce the number of moles of H3PO4 determined from the question above which the answer is 2.34 for above.

**Chemistry help!!**

Phosphoric acid, H3PO4, has some important applications. It can be used to produce fertilizers and it is present in soft drinks. Phosphoric acid can be made from phosphorus in a two step process: Reaction 1: P4 + 5 O2 --> P4O10 Reaction 2: P4H10 + 6H2O--> 4H3PO4 A ...

**Chemistry help!!**

Potassium perchlorate decomposes as follows: KClO4 (s) --> KCl (s) + 2 O2 (g) If 269 mL of wet O2 (g) is collected over water at 25 c (vapor pressure= 23.8 torr) and the barometric pressure is 748.0 torr, how many grams of potassium perchlorate have decomposed?

**Chemistry **

Potassium perchlorate decomposes as follows: KClO4 (s) --> KCl (s) + 2 O2 (g) If 269 mL of wet O2 (g) is collected over water at 25 c (vapor pressure= 23.8 torr) and the barometric pressure is 748.0 torr, how many grams of potassium perchlorate have decomposed?

**Chemistry**

What volume of N2O (s) will be generated if 3.13 g of NH4NO3 (s) decomposes at 1.00 atm and 50 degrees celsius, given the following decomposition reaction: NH4NO3 (s) --> N2O (g) + 2 H2) (l)?

**Chemistry**

Why doesn't acetylation occur twice on the same ring? Please help, I have no idea.

**Physics**

In a rectangular coordinate system, a positive point charge 5.0 nC is placed at the point x=0, y=2.0 cm, and a negative point charge -5.0 nC is placed at x=0, y=-2.0 cm. Both charges have masses 4.0x10^-3 g. Point P is at x=3.0 cm, y=2.0 cm. The electric potential at infinity ...

**Chemistry**

draw the product of di-acetylation of biphenyl. Explain why acetylation does not occur twice on the same ring. I have no idea how to do this

**Chemistry**

How would you know which one is the polar solute?

**Chemistry**

yes it is a polar solvent

**Chemistry**

Consider compounds trans-4-tert-butylcyclohexanol and 4-tert-butylcyclohexanone below. Using silica gel TLC plates, which of these two compounds will have the higher Rf value when dichloromethane is the developing solvent? Why? Does it possibly have to do with the polarity?

**Chemistry**

Based on chemical structures, explain why acetophenone is only separated at the end by distillation. The mixture was acetophenone and ethyl trimethylacetate

**Organic Chemistry**

Explain why the formation of one geometric isomer is favored over the other?

**Calculus**

find the point on the plane 5x+4y+z=12 that is nearest to (2,0,1)

**Chemistry**

What is the value for Kb for the formate anion, HCOO-? Ka(C7H5O2)=2.1x10^-4.

**Calculus**

Compute the curvature. r(t)=(t^2,2t^3/3) t >0 The answer is 1/2t(1+t^2)^3/2 I have tried multiple times but i cannot arrive to this answer.

**Chemistry**

If all of the SCN- was not converted completely converted to FeNCS^2+ when the calibration curve was prepared, would this raise or lower the value of Keq? Explain

**Biology**

Use your understanding of natural selection to describe how the following trait might have evolved: Plants have pores on the surfaces of their leaves that allow carbon dioxide into the leaf (for photosynthesis), but also allow water to escape. Land plants have guard cells ...

**Chemistry**

What is the pressure of 1.78 g of nitrogen gas confined to a volume of .118 L and 25 degrees Celsius?

**chemistry**

nevermind i figured them out

**chemistry**

Write the molecular,complete ionic, and net ionic equations for the reactions that occur, if any, when solutions of the following substances are mixed: a) nitric acid and potassium carbonate b) sodium bromide and lead nitrate c) acetic acid and calcium hydroxide d) calcium ...

**general chemistry**

How many oxygen atoms are in 3.90 g of quartz?

**math**

I am solving a problem and have -cos(a)=-1/2. How do I solve for a?

**ap calc**

Find the area of the shaded region, bounded by the parabola 16y=5x^2+16 and the lines y=0, y=6, and x=5. I broke the figure up into two parts and got 3102/5. It seems like a large answer am I correct? Your help is greatly appreciated.

**AP Calc**

If y= (e^x-e^-x)/(e^x+e^-x), then y'= I took the derivative and got: y'=(e^x+e^-x)(e^x+e^-x)-(e^x-e^-x)(e^x-e^-x)/(e^x+e^-x)^2 I know the correct answer is 4/(e^x+e^-x)^2

**Government**

What is one specific example of why a person would be summoned to the Erie County Supreme Court? I know that the Erie County Supreme Court deals with criminal and civil cases.

**Psyc, statistics**

Introduction to Hypothesis Testing In an article entitled “Science and ethics in conducting, analyzing, and reporting psychological research” in the journal Psychological Science (1994), psychologist Robert Rosenthal examines the relationship between a researcher&#...

**Math**

Dorothy and Rosanne are baking cookies for a party. Working alone, Rosanne can finish the cookies in 6 hours. Dorothy can finish them in 8 hours if she is working alone. How long will it take them to bake the cookies if they are working together? Round your answer to the ...

**English**

Decide which of the two reasons offered in each instance will be more persuasive to the specified audience.Write out the implied warrant for each "because" clause and explain whether the specific audience will likely grant it or not. 1)Audience:people who advocate a ...

**health and diseases**

this was not very helpful but thanx anyways.

**health and diseases**

I need a little help with an analogy for Nephrogenic diabetes insipidus. I'm not sure excatly how to make an analogy for that. i don't know what to compare Nephrogenic diabetes insipidus to. please help

**Healthcare**

I agree with everything above....that is exactly how i feel! i have the same problems!

**Healthcare**

I agree with everything above....that is excatly how i feel! i have the same problems!

**ethics**

Things don't get fixed over night. Sounds like some people need to get a little more patience. Obama is doing a fine job.

**ethics**

Things down get fixed over night. Sounds like some people need to get a little more patience. Obama is doing a fine job.

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