# Posts by hannah

Total # Posts: 3,347

**chemistry**

If a saline solution has a concentration of 0.25 g per mL, calculate the following. a) The concentration of this solution in %w/v. b) The concentration of this solution in grams per litre (g/L). c) The concentration of this solution in milligrams per mL (mg/mL).

**please check my answer**

Consider the following equations. N2H4(l) + O2(g) N2(g) + 2 H2O(l) ÄH = -622.2 kJ H2(g) + 1/2 O2(g) H2O(l) ÄH = -258.5 kJ H2(g) + O2(g) H2O2(l) ÄH = -187.8 kJ Use this information to calculate the enthalpy change for the reaction shown below. N2H4(l) + 2 H2O2(l...

**Math Algr.2**

Convert to standard form (AX+BY=C) 1.y=3/2x+6 2. 2/3y=2x-5 3.7y-21=1/2x 4.-2/3x+3/4y=1 Convert to Slope/intercept form (y=mx+b) 1.3x-27=14 2.-9y-6x-18=0 3.8-2x+4y=0 12x=4y-8 I need help going through this because I am not sure if I am doing everything right and I also don'...

**chem- i reallyneed help**

oops that's me ^

**chem- i reallyneed help**

Consider the following equations. N2H4(l) + O2(g) N2(g) + 2 H2O(l) ÄH = -622.2 kJ H2(g) + 1/2 O2(g) H2O(l) ÄH = -258.5 kJ H2(g) + O2(g) H2O2(l) ÄH = -187.8 kJ Use this information to calculate the enthalpy change for the reaction shown below. N2H4(l) + 2 H2O2(l...

**chem urgent!**

Set up a Hess's law cycle, and use the following information to calculate ÄH°f for aqueous nitric acid, HNO3(aq). You will need to use fractional coefficients for some equations. 3 NO2(g) + H2O(l) 2 HNO3(aq) + NO(g) ÄH° = -138.4 kJ 2 NO(g) + O2(g) 2 NO2(g...

**chem**

(a) When a 4.75-g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter (see figure), the temperature drops from 23.0‹C to 16.6‹C. Calculate ƒ¢H (in kJ/mol NH4NO3) for the solution process NH4NO3(s) ¨...

**Algr1**

Find the x and y intercept of the equations. 1.5x+6y=-30 2.x-4y=-16 3.-3x+4y=12 How would I solve these and what is the anwsers

**Algr1**

Find the x and y intercept of the equations. 1.5x+6y=-30 2.x-4y=-16 3.-3x+4y=12 How would I solve these and what is the anwsers

**Algr.1**

Find the x and y intercept of the equations. 1.5x+6y=-30 2.x-4y=-16 3.-3x+4y=12 How would I solve these and what is the anwsers

**Chemistry(Please check)**

Thank you!

**Chemistry(Please check)**

For an experiment on specific heat capacities my data for measured specifi heats was consistently higher than the accepted values. I am not sure why this is. Would it be because my initial temperature that I started the experiment with was higher than it should have been? ...

**Chemistry(Please, please help)**

I am trying to draw a constitutional isomer for the compound CH3CH=CHCH3 but I am having some trouble. H-C-C=C-C-H I drew the first compound like this with more hydrogens on the Cs. How could I draw another strucutre?

**Math(Please check)**

Please diregard, I figured out my mistake.

**Math(Please check)**

For an experiment on specific heat capacities of metal in physics, I am trying to calculate my percent error but am having some trouble. After collecting my experimental data for c (cal/g) for the object that was used which was aluminum my results are: trial 1 = .19 trial 2...

**Math/Physics(Please check work)**

Please disregard. I figured out my mistake.

**Math/Physics(Please check work)**

For an experiment on specific heat capacities of metal in physics, I am trying to calculate my percent error but am having some trouble. After collecting my experimental data for c (cal/g) for the object that was used which was aluminum my results are: trial 1 = .19 trial 2...

**math**

964

**please help**

When is the best time to read review or discussion questions? A. Immediately after you have finished all of the reading. B. After you write your notes. C. Before you begin any detailed reading. D. Throughout your detailed reading.

**Chemistry(Please help)**

ok thank you and for the specific rotation of L-erythrose 4-phosphate would it be the same as for D-erythrose 4-phosphate which I determined was 50 or would it be -50?

**Chemistry(Please help)**

The path of length was given in cm so I converted it to dm but I am not sure if I calculated the concentration correctly. A 50 gram sample was dissolved in 10 mL solution so would I do 50/10?

**Chemistry(Please help)**

Oh ok, the question asks me to find the specific rotation for D-erythrose 4-phosphate which I determined was 50 and then it asks me to find the specific optical rotation for L-erythrose 4-phosphate so I thought that it would be a different formula.

**Chemistry(Please help)**

I know that to calculate the specific rotation for a compound you do observed rotation / path length(dm) * conc. (g/ml). I am confused about how to calculate the specific optical rotation for a compound. Thank you for your help!

**Chemistry(Please check)**

Determine if the equation is SN1, SN2,E2 or E1. CH3CH2O- + CH3CH2BR = CH3CH2OCH2CH3 + BR- I think that this is SN2. Would you agree?

**math**

20 Minivans

**Algebra 1**

A 30-pack of blank CDs cost $9.50. A 50-pack of CDs cost $13. How can you tell which is the better buy?

**Trigonometry**

The average temperature, in °F, for Atlanta, GA is modeled by the sinusoidal function y = 18.25 sin(pi/6 t - 2.09) + 61.15 where t is the time in months and January is t=1. What is the average Temperature for the month of February? Using the same equation, what is the ...

**Chemistry(Please answer)**

How many chirality centers does the compound 1,3-dibromo-2,4-dichloro-5-fluorocyclopentane have? This compound has three different elements, a Br which is repeated twice, a cl which is also repeatd twice, and a fluorine. I was thinking that the number of centers would be 3 ...

**Math**

850 hectare = ? km^2 850 ha (1 km/100 ha) = 8.5km^2 Is this conversions correct? not just the answer but also how I got to the answer. PLEASE let me know if im on the right track, thanks!

**Math**

Change 300 mm3(cubed) to cm3(cubed). I have no idea how to work this out. Any help you can give me would be greatly appreciated!! Thanks

**Chemistry(Urgent, please check)**

For C4H10O a constitutional isomer can be written as C-C-C-C-O-H with hydrogens also coming off of the 4 carbons. I know that this is an alcohol. I need to know if there are stereoisomers for this other than conformers. I think that there are stereoisomers because you can just...

**Chemistry(Please check, thanks)**

For C4H10O a constitutional isomer can be written as C-C-C-C-O-H with hydrogens also coming off of the 4 carbons. I know that this is an alcohol. I need to know if there are stereoisomers for this other than conformers. I think that there are stereoisomers because you can just...

**math**

There were 12 boys and 18 girls in a class. Then, 3 more boys joined the class and 2 girls left. What is the ratio of the number of boys to the number of girls in the class now?

**Econ**

what is the purpose of the labor law- executive order- created in 1965

**Math**

For an experiement to test elastic collision, ball 2 was at rest and ball 1 was released from a certain height and distance and hit ball 2. A set of measurements were collected which was v1 and v2 prime for each ball. I need to calculate the kinetic energy before and after ...

**Math(Please help, thank you)**

Im alittle confused because my data sheet gives values for mass, height, diameter and then v1 and v'2. So would v1 ball one and V'2 ball two?

**Math(Please help, thank you)**

For an experiement to test elastic collision, ball 2 was at rest and ball 1 was released from a certain height and distance and hit ball 2. A set of measurements were collected which was v1 and v2 prime for each ball. I need to calculate the kinetic energy before and after ...

**Chemistry(Please help)**

thank you

**Chemistry(Please help)**

I am trying to figure out what functional group the compound CH2ClCH3 is in. I know that it is not a ketone, alcohol, ester, ether, amine, amide, ect..I do not know what it could be.

**Chemistry(Please check)**

identify the functional group and indicate polar bonds by assigning partial positive and negative charges. 1) The structure CH3OCH3 is drawn out and I know that this is an ether because the O is bonded to two carbons but I am not sure how to assign the charges. I think that ...

**Chemistry**

I am trying to figure out what functional group the compound CH2ClCH3 is in. I know that it is not a ketone, alcohol, ester, ether, amine, amide, ect..

**Chemistry**

identify the functional group and indicate polar bonds by assigning partial positive and negative charges. 1) The structure CH3OCH3 is drawn out and I know that this is an ether because the O is bonded to two carbons but I am not sure how to assign the charges. I think that ...

**Physical science.**

A skydiver who jumps out of a plane that has a forward velocity of 40 m/s. That means that the skydiver has a forward velocity of 40m/s. Ignore the air resistance. The questions: What difference is there between the downward velocities of the skydiver who jumped out of the ...

**Chemistry(Please answer, thanks)**

So then they are not conformers or constitutional isomers correct?

**Chemistry(Please answer, thanks)**

I have to answer the following questions about C3H7Cl: Are there different constitutional isomers for this formula, are there different cis/trans isomer, and are there different conformers? I know that C3H7Cl can be drawn two ways: H-C-C-C-Cl With H's above and below the ...

**Chemistry**

I have to answer the following questions about C3H7Cl: Are there different constitutional isomers for this formula, are there different cis/trans isomer, and are there different conformers? I know that C3H7Cl can be drawn two ways: H-C-C-C-Cl With H's above and below the 3...

**Science**

Which of these statements concerning the interaction of light waves with the glass of a greenhouse is correct? A. Infrared is transmitted through the glass and is changed to heat B. The glass reflects ultraviolet waves C. Visible light is transmitted through the glass Or D. ...

**career**

your link just brought up the main google page

**career**

Do veterinarians get paid during residency? If so how much?

**physics**

A 410-m-wide river has a uniform flow speed of 2.0 m/s through a jungle and toward the east. An explorer wishes to leave a small clearing on the south bank and cross the river in a powerboat that moves at a constant speed of 7.9 m/s with respect to the water. There is a ...

**Physics(Please just check, thanks)**

Please diregard. Thank you!

**Physics(Please just check, thanks)**

Using a force table the direction and magnitude had to be found for the following measurements: F1 = 200 grams at 30 degrees; F2 = 200 grams at 120 degrees The magnitude and direction found was 280 grams at 257 degrees. Using the magnitude and direction of F1 and F2 I need to ...

**Physics(Please help, thank you)**

Oh ok I got 283 and 75 degreed from usng the Rx an Ry equations and then doing tan^-1(Ry/Rx), so 283 and 75 is my answer?

**Physics(Please help, thank you)**

Using a force table the direction and magnitude had to be found for the following measurements: F1 = 200 grams at 30 degrees; F2 = 200 grams at 120 degrees The magnitude and direction found was 280 grams at 257 degrees. Using the magnitude and direction of F1 and F2 I need to ...

**Chemistry Help? Thanks**

At what temperature do KCL and KNO3 have the same solubility If a saturated solution of KNO3 at 20.0 C is heated to 80.0 how much more could be dissolved? If a saturated solution of KCL at 90.0 C is colled to 30.0 C how much of the solid will precipitate? How much NaCL will ...

**math**

the world record for the 100 meter butterfly swim set in 1999 was 51.81 sec. What was the average rate per second? thx:)

**ela**

The narrator points out that Emily, who has only recently blossomed, struggled with her appearance in the past. What this means..

**Chemistry(Please check)**

an acid with the equilibrium concentration is listed below: 1) HA + H2O = H3O^+ + A- HA= 10^-1 M, H3O=10^-3M, A=10^-3M Calculate the Ka and pKa for the acid. Ka=[10^-3][10^-3] / [10^-1] = 1.00 X 10^-5 pKa = -log[1.00 X 10^-5] = -1.00 Did I do this correctly for the Ka and pKa?

**Chemistry(Please check)**

List the conjugate base for the following acids: 1) Acid = CH3CH2CH2NH3^+ Conjugate base = CH3CH2CH2NH2^- 2) Acid = CH3CH2CH2OH2^+ Conjugate base = CH3CH2CH2OH^- Are my answers correct? Thank you!

**English**

djssdjssdlawljdwjiqqwewwjliiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiid.,m c.makoooowdijfehfjdakwsQ'

**Math(Please check, urgent)**

Please disregard. Thank you.

**Math(Please check, urgent)**

I was using this equation as an example to try to help myself understand something but I think I may have set it up incorrectly. What I am trying to do is find the y max of a projectile using the equation y = yo + (vo sin Q ) t -1/2gt^2. I keep plugging in my values for the ...

**Math(Please check, urgent)**

Yes but I always set it up incorrectly. so [76.95 +/- sqrt (76.95^2 - 4(4.9)(-1.5)] / 9.8 Did I set this up correctly?

**Math(Please check, urgent)**

y=1.5 + 76.95t-(1/2)(9.8)t2 = 303.6 I am not sure how to arrive at this answer. I am confused because there is a t and a t^2. Thank you for your help!

**physics**

A motorboat accelerates uniformly from a velocity of 6.6 m/s to the west to a velocity of 1.3 m/s to the west. If its acceleration was 2.1 m/s2 to the east, how far did it travel during the acceleration? Answer in units of m.

**physics**

A motorboat accelerates uniformly from a velocity of 6.6 m/s to the west to a velocity of 1.3 m/s to the west. If its acceleration was 2.1 m/s2 to the east, how far did it travel during the acceleration? Answer in units of m.

**Math(Please answer)**

This is the same equation as before just with different numbers. y=yo + (vo sin Q) t - 1/2gt^2 This time the numbers are: 0 = 1.005 + (3.021 sin 30)t - 1/2(9.8)t^2 4.9t^2 - 1.5105 - 1.005 = 0 This is the part where I am stuck. Did I do this correctly? sin 30 = 0.50 X 3.021 = 1...

**Physics(Please answer, thank you)**

How do you determine the ymax? I know you have to use Q which I have values that were given to me as well as vo values but I am not sure what to do with these values. Physics - drwls, Saturday, September 15, 2012 at 1:29am Define your terms. I have no idea what you are talking...

**Physics(Please answer, thank you)**

How do you determine the ymax? I know you have to use Q which I have values that were given to me as well as vo values but I am not sure what to do with these values.

**Math**

This is the same equation as before just with different numbers. y=yo + (vo sin Q) t - 1/2gt^2 This time the numbers are: 0 = 1.005 + (3.021 sin 30)t - 1/2(9.8)t^2 4.9t^2 - 1.5105 - 1.005 = 0 This is the part where I am stuck. Did I do this correctly? sin 30 = 0.50 X 3.021 = 1...

**Algebra 2 (Math)**

If A=(0,-17), B=(4,-5), and C=(12, -1), what is the length of the altitude from C to AB

**Math (Algebra 2)**

The points (2,1), (4,0), and (-4,k^2) are collinear. What is the value of k?

**Physics(Please help)**

How do you determine the ymax? I know you have to use Q which I have values that were given to me as well as vo values but I am not sure what to do with these values.

**Math**

Thank you!

**Math**

I have to calculate the percent error for my experiment and I just wanted to make sure that I am doing it correctly. My value was 1.376 and the accepted value was 1.371 so I did [1.376 - 1.371] / 1.371 = 0.0036 X 100 = 0.36% Did I do this correctly?

**Math(Please check)**

This is the same equation as before just with different numbers. y=yo + (vo sin Q) t - 1/2gt^2 This time the numbers are: 0 = 1.005 + (3.021 sin 30)t - 1/2(9.8)t^2 4.9t^2 - 1.5105 - 1.005 = 0 This is the part where I am stuck. Did I do this correctly? sin 30 = 0.50 X 3.021 = 1...

**Chemistry**

Thank you very much!!

**Chemistry**

I have to draw a skeletal, kekule, and lewis structure for this but I am having some difficulty because there is so much going on in the structure. Do you know of any websites that could show me examples of these types of condensed structures?

**Chemistry**

In the condensed structure CH3CH2CHCH double bonded to CHCH(CH3)2 ! CH3 What does it mean when the CH3 is in () followed by the 2?

**Chemistry(Please check)**

Last question, I just want to make sure I understand the concept of hybridization. For carboxylic acid the hybridization is: CH3= sp3 because there are only single bonds COOH= Sp2 because the oxygen is double bonded to the C Is this correct? Thank you for checking my work!

**Chemistry(Please check)**

What is the hybridization of each carbon in the molecule of ethanol. CH3 = sp3 CH2OH = sp3 I think that the carbons are all sp3 because there are only single bonds in this molecule. Is this correct?

**Math(Please help)**

Ok so just to make sure I take the square root of 1.005/4.9= 0.45 which would be both positive and negative but I only take the negative correct? Thank you for your help. This makes sense now because I have to compare this value to the actual which was 0.44 so I am not to far ...

**Math(Please help)**

The 1.005 was the value given for yo, the angle given was 0 and vo was 3.107. The t I just took from the equation y=yo + (vo sin Q) t -1/2 gt^2. I need to find t using this equation but I wasn't sure how to do it.

**Math(Please help)**

Using the equation y=yo + (vo sin Q) t - 1/2gt^2 I have to find t. The values for y, yo and vo were given to me. So I set the equation up like this: 0=1.005 + (3.107 sin 0) t - 1/2(9.8)(t^2 The sin of 0 is 0 times 3.107 is 0. So 0 = 1.005 t - 4.9 t^2 Now I am stuck. I am not ...

**Chemistry**

Oh ok I understand thank you!

**Chemistry**

Sorry didn't get to finish. CH2 CH2 ! ! CH2 CH2 Each CH2 going from left to right has a single bond as well. I think this is an alkane but I am not sure. I only think this because it only has single bonds of hydrogen and carbon. Is this correct?

**Chemistry**

Classify the following: 1) CH2 CH2 ! ! CH2

**Chemisty**

Classify the following: 1)CH3CHCH2COOH ! CH3 I think this is a carboxylic acid because of the COOH attached. Would you agree?

**chemistry**

ok thank you!

**chemistry**

Is that a functional group?

**chemistry**

Classify the following: 1) CH3CN There is a triple bond between the C and N. I am really not sure what compound this is.

**Chemistry(Please check)**

Thank you very much!!

**Chemistry(Please check)**

Classify the following as ether, ketone, ester, amide, etc. 1) CH3CH2CNH2 !! O The !! represents a double bond and it is below the CN I think this is an amide. 2) CH3COCH3 !! O The doube bond is below the CO I think this is an ester. 3) CH3CCH3 !! O The double bond is below ...

**Physics(Please help)**

using the equation y=yo + (vo sin Q) t - 1/2gt^2 I have to find t. The values for y, yo and vo were given to me. So I set the equation up like this: 0=1.005 + (3.107 sin 0) t - 1/2(9.8)(t^2 The sin of 0 is 0 times 3.107 is 0. So 0 = 1.005 t - 4.9 t^2 Now I am stuck. I am not ...

**Physics(please check)**

Please diregard. Thank you!

**Physics(please check)**

X=(Vo cos Q) t X=(3.107 cos 0)(0.443) I just wanted to make sure that I put this equation into my calculator correctly. I have a TI-30 so first I put in 0 then cos to get 1. Then I multiplied by 3.107 to get 3.107 and then multiplied by 0.443 to get 1.376 . Did I do this ...

**Math**

Plz help lisa is painting a fence that is 26 feet long and 7 feet tall. A gallon of paint will cover 350 square feet. Write and solve a proportion to determine how many gallons lisa will need.

**Math**

An assembly line worker at rob's bicycle factory adds a seat to a bicycle at a rate of 2 seats in 11 minutes. Write a proportion relating the number of seats s to the number of minutes m. At this rate how long will it take to add 16 seats? 19 seats?

**Chemistry(Please check)**

Classify the following functional groups: 1)CH3CH = CH2 I think this is an alkene 2) CH3CHCH3 I think it is an alcohol. ! OH Would you agree with my answers?

**Organic chemisty(Please check)**

Do you have to show the R? I need to show the kekule structure for CH3CONH2. I know how to start it off Im just not sure about the NH2. The N would be connected to a carbon on the left side correct?