chemistry! URGENT

60,135 results, page 28

CHemistry

I did a project for lab chemistry where my aim was to see which substance, from a selection of 4 chlorides, recrystallises from a solution to form the most crystals. The 4 chlorides were KCl, NaCl, MgCl2 and CaCl2. KCl and NaCl didn't form any crystals, they formed a saturated...

chemistry

A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 525 nm , how many photons are emitted per second? okay so i do: ((6.626*10^-34)(3.00*10^3))/(5.25*...

chemistry

Ca + Br2 --> CaBr2 its synthesis and the reason the reaction happens is stable electron configuration but i don't understand why. Responses chemistry - DrBob222, Wednesday, January 21, 2009 at 10:06pm Synthesis because it's two elements combining to form a single product. ...

Chemistry(Please help)

1) Nitrosyl chloride (NOCl) decomposes at high temperature. The equation is 2 NOCl (g) -> 2 NO (g) + Cl2 (g) at 227oC Using delta Ho = 81.2 kJ and delta So = 128 J/K, calculate the value of the equilibrium constant for this reaction. I do not know how to start this problem ...

Chemistry

a) The element with the greatest density is osmium, which has a density of 22.6g/cm3. calculate the mass of 32.1 cm3 of osmium. Answer: 22.6g x 32.1 = 725.46 Did I have right answer? b) A team of students determined the density of a sample of wood to be 0.52g/cm3. A handbook ...

Chemistry (please help!!)

a stressed chemistry student is hyperventilating into a paper bag. The student stops to wip his brow after a few breaths, and the bag is at 5.7 KPa and the temperature in the lecture hall is 24 degrees C. The bag is 0.75 L full. The student then goes at it again, and ...

Chemistry

High-pressure liquid chromatography (HPLC) is a method used in chemistry and biochemistry to purify chemical substances. The pressures used in this procedure range from around 500 kilopascals (500,000 Pa ) to about 60,000 kPa (60,000,000 Pa ). It is often convenient to know ...

chemistry

High-pressure liquid chromatography (HPLC) is a method used in chemistry and biochemistry to purify chemical substances. The pressures used in this procedure range from around 500 kilopascals (500,000 Pa ) to about 60,000 kPa (60,000,000 Pa ). It is often convenient to know ...

English

I still have a few doubts on school rules. I hope you can have a look at them. It's urgent. 1)You mustn't dirnk or eat during lessons/school hours. 2) You mustn't ask questions when your teacher explains/is explaining/during explanations. 3) You must take notes if you want to ...

Chemistry

Income tax for some states is computed by taking 3% of the excess income over $3,000 plus 1% of the first $3,000. How much tax is charged on a income of $12,000? 12,000 1 percent on first 3000 3 percent of (12,000 - 3000) I'm trying to figure the relationship between income ...

organic cehmistry

I am totally lost on the subject of Fischer projection. I have no clue on where to begin solving : (S) 3-chloro-1-penten-4-yne http://www.mhhe.com/physsci/chemistry/carey/student/olc/ch07projections.html

chemistry

I wanted to check my True and False Chemistry HW. I am not 100% they are correct. 1.the number of neutrons in an atom is reffered to as its atomic number False 2.the periodic table is arranged by increasing atomic number True 3.atomic number is equal to the number of electrons...

chemistry

I asked this question earlier that drbob explained but i still do not really understand what to do. can you please make it clearer? the average pH of healthy human blood is 7.4. how many moles of H+ ions are free in your blood. The average person has approx. 5 L of blood. ...

lighthouses

Hi my son has to do a lighthouse for a school project and it has to really light, I'm not really sure how to go about this project or what materials he will need. Can anyone offer any help Believe it or not here is a site on how to build a model lighthouse...simple ...

chemistry -------------chemistry

If a flame on the candle burns red , how does energy of that flame compare to that of the Bunsen burner flame ? and why ? ans:The Bunsen burner flame has higher temperature than candle’s flame . Because flame of candle emit red ,and red has the least energy in visible light.

Chemistry

Hi! I'm in chem class and I don't know the answer to these questions I have several metal alloys and have to tell their general elements that make them up for example bronze - copper and tin What is the elements that make up Pewter? Also I was woundering if someone can tell me...

chemistry

Posted by Brunette on Sunday, October 14, 2012 at 10:42pm. Values of the rate constant for the decomposition of N2O5 at four different temperatures are as follows: T(K) k(s^-1) 658....2.14*10^5 673....3.23*10^5 688....4.81*10^5 703....7.03*10^5 The activation energy is 1.02*10...

chemistry

Lactic acid, HC3H5O3(aq) is a weak acid that gives yougurt its sour taste(Yeeeeecccckkk). Calculate the pH of a 0.0010 mol/L solution of Lactic acid. The Ka for lactic acid is 1.4 x 10^-4 For Further Reading chemistry - DrBob222, Saturday, April 5, 2008 at 7:39pm Let's call ...

English

Can you help me determine if I chose the correct/incorrect sentences appropriately. It’s really urgent. 1)Jenny, 13, says “My favourite subject is English. We all have to learn English in my country because it is very difficult to find a job if you don’t know it. Jenny ...

osmotic pressure chemistry.

I have a question about osmotic pressure. I took a test in chemistry and this was a multiple choice question. It said given the molar mass of each solution, which one had the high osmotic pressure. So a high osmotic pressure, means a high molar mass or a low molar mass?

maths

In a class of 60 students, the number of students who passed biology is 6 more than the number who passed chemistry. Every student passed at least one of the two subjects and 8 students passed both subjects. I) how many students passed biology? ii) how many students passed ...

Chemistry

In winemaking, the sugars in grapes undergo fermentationby yeast to yield CH3CH2OH and CO2. During cellularrespiration, sugar and enthanol are "burned" to water vapor andCO2. A) Using C6H12O6 for sugar, calculate ÄH of fermentation and of respiration(combustion). B) Write a ...

chemistry

The letters CHEMISTRY were spray painted in blue paint on the snow. After a while the sun comes out and the snow under the blue paint melts while the snow around the letters do not. Why did the snow under (rather than around) the blue paint melt?

planning

Ms. Sue, you told me last time to search up my college to see what courses are required for hygienist, and so this is what I got. 2. The course choices that I make today lead to the fulfillment of this dream by them providing all the knowledge that I need to know to become ...

Science (Chemistry)

I did not understand the lesson today in my Chemistry I honors class. We went over the Law of Conservation of Mass for roughly 15 minutes and he gave us this worksheet. Could someone please display how to do this, I'll pull a problem from the worksheet. When 9.56g of Copper ...

Spanish (URGENT)

Habia una vez hay un conejo pequeno. El no estaba contento. Queria mirar como les otros animales. Cuando él vio Mr. Bushy Tail, la ardilla, él quise una cola que se parecio las ardillas. Entonces, él vio Mr. Porcupine y el quise (quills). Entonces él pasó Mrs. PuddleDuck ...

Chemistry

DrBob222, I don't know how to solve this problem either. And yes, this is the question for this problem. I even double check it. Please help. Chloroform (CHCL3) has a normal boiling point of 61 'C and an enthalpy of vaporization of 29.24 kJ/mol. What is the value of delta Gvap...

Animal Physiology HELP!!!!!!!!!!

Please help me!!! What are the answers to these Animal Physiology questions? Urgent..... A decrease in the partial pressure of carbon dioxide in the lungs is referred to as a) Respiratory acidosis b) Hypercarbonia c) Hyperoxia d) Hypercapnia ...

chemistry

3.) One method used in the eighteen century to generate hydrogen was to pass steam through red-hot steel tubes. The following reaction takes place: 3Fe(s)+4H20(g)--->Fe3O4(s)+4H2(g) 1. What volume of hydrogen at STP can be produced by the reaction of 6.28 g of iron? 2. What...

Physical Chemistry

In my physical chemistry book, I'm reading about "Margules Equations": ln γA = ΒxB2 ln γB = ΒxA2 I don't understand where these equations come from. How is it known that there is a single constant Β that satisfies both relationships?

statistics

Leslie took two midterm exams and earned the following scores: 82 on the chemistry exam (class distribution: μ = 75, σ = 6.25) and 63 on the physics exam (class distribution: μ = 59, σ = 3.57). Rounding to two decimal points, on which exam should Leslie get...

Chemistry

How do you calculate alkalinity in chemistry? Ex: List the values for total alkalinity for Sample A and Sample B A 104 drops of titrant (5.25mL) 3 drops of C20 H14 O4 B 81 drops of titrant (4.25mL) 3 drops od C20 H14 O4

Please Help Very Urgent

Hello, I am new to this website. I visited this website few times.I have some HEALTH questions.I am sick since 5 days.This is about my HEALTH.Please answer my questions if you know the answer to it! My problem is: I was chewing the BIG RED CINAMMON FLAVOR CHEWING GUM.I did not...

Chemistry/English

In chemistry we are writing a paper about an inventor.. We have to have some back ground info.. what they invited. how there time affected there inventions and if there inventions where a great success and so on so forth. What would be a good way to set this paper up. Its a ...

lab chemistry

I did a project for lab chemistry where my aim was to see which substance, from a selection of 4 chlorides, recrystallises from a solution to form the most crystals. The 4 chlorides were KCl, NaCl, MgCl2 and CaCl2. KCl and NaCl didn't form any crystals, they formed a saturated...

chemistry

If your car gets 21.4 mpg, how many L of CO2, will you release into the atmosphere, if you drove the 1280miles from Towson University to key West Florida for a much needed break after taking Chemistry 121? Assume 1.05atm and 17.0C. What would your carbon load be in lbs (lbs of...

chemistry

If your car gets 21.4 mpg, how many L of CO2, will you release into the atmosphere, if you drove the 1280miles from Towson University to key West Florida for a much needed break after taking Chemistry 121? Assume 1.05atm and 17.0C. What would your carbon load be in lbs (lbs of...

chemistry

If your car gets 21.4 mpg, how many L of CO2, will you release into the atmosphere, if you drove the 1280miles from Towson University to Key West Florida for a much needed break after taking Chemistry 121? Assume 1.05atm and 17.0C. What would your carbon load be in lbs (lbs of...

Spanish (URGENT)

Can someone please check my work? Answer the following questions in a complete sentence. 1. ¿A qué hora duermes por la noche? Duermo a las once por la noche. 2. ¿Dónde almuerzas con tus amigos? Mis amigos y yo almorzamos en la cafetería. 3. ¿Cuándo vas al teatro? Yo ...

Chemistry

My chemistry is bad. I know these are very easy but I cannot solve them . 1. a) Prepare 200 ml of 2 M HCl solution from stock bottle containing 37% w/w HCl and d = 1.2 (g/ml). MWHCl = 36.5 g b) Calculate M of 37% w/w HCl solution? d= 1.2, then solve the above problem 2. a) ...

English

I'd like you to check these sentences for me, please. Thank you very much. It's urgent! 1) Virginia Woolf wanted to explore man's mental experience following what Joyce had already done in England Proust in France. S 2) he abondoned traditional writing techniques and turned to...

science

Can you direct me to a site(s) which can help with college chemistry and statistics? Here are a couple of good chemistry sites that pretty well cover the waterfront. I don't know any stat sites but if you will repost with the subject line of "math" I'm sure someone will help ...

Organic Chemistry/Biology

My text has a review of some chemistry before getting into the biology bit. I have come to a question "what are 3 characteristics/features of an organic compound." My book seems to only have the general they all have carbon. The rest goes into depth about the different classes...

chemistry

The "Chemistry in Focus" segment A Magnetic Moment discusses the ability to levitate a frog in a magnetic field because electrons, when sensing a strong magnetic field, respond by opposing it. This is called diamagnetism. Atoms that are diamagnetic have all paired electrons. ...

chemistry/stiochiometry

for instance Will write a problem. Now, I don't just want the answer, I want to know how to know which substances, and processes in steps and don't spare detail. I am going through high school chemistry. somehow i PAST MY Stoichiometry test. now i am ready for titration of ...

Chemistry

I am unsure how to write hypotheses for my experiments for pH, salinity using tirration(agno3), turbidity, conductivity of water samples. The teacher wants the hypothesis in this format Hypothesis format - If (relationship between independent variable and dependent variable) ...

English

I still have a few parts I'm unsure of. I really hope you can help me. It's urgent, especially the last paragraph n.7 1)In the second stanza, the soldiers succeed in putting on their clumsy gas masks. Someone, however, is still crying out for help, unable to move quickly and ...

Maths

In a class of 60students,the number of student passed Biology is 6 more than the number of student passed Chemistry,8 student passed both subject.How many student passed Biology,how many student passed Chemistry,how many student passed only one subject?

Chemistry

12.

chemistry

what is (1.2*10^2)*(8.9*10^2)

chemistry

in chemistry what is aq

Chemistry

what is mm^2?

chemistry

how do i d

chemistry

Thanks for the Help

Chemistry

Mg>Al>Ca>Rb>I

Chemistry

What is pH

Chemistry

X=\MX=\MX=\M What is this?

Chemistry

1.42 g/cm^2 to mg/mm^2

chemistry

How many \({\rm m}^{3}\) are in 7.40 \({rm cm}^{3}\)?

chemistry

when does 4+4=9

Chemistry, pH

What is the (OH-) when pH = 4.25

chemistry

what is the

chemistry

3.5g

Chemistry

1.0 x 10^5 mL=m^3

chemistry

how many g/ml are there in 1M?

chemistry

thanks!

Chemistry

In winemaking, the sugars in grapes undergo fermentation by yeast to yield CH3CH2OH and CO2. During cellular respiration, sugar and enthanol are "burned" to water vapor andCO2. A) Using C6H12O6 for sugar, calculate ÄH of fermentation and of respiration(combustion). B) Write a...

chemistry

Strychnine, C21H22N2)2(aq) is a weak base but a powerful poison. Calculate the pH of a 0.001 mol/L solution of strychnine. The Kb of strychnine is 1.0 x 10^-6 DrBob222, I am planning on obtaining a pHD in about nine years:P Can you give me some advice on how to be that 1% of ...

Chemistry

For chemistry I am supposed to convert 0.001 348 grams to milligrams. I know how to convert grams to milligrams, but I don't get what's with the 0.001. Does this mean it should be .348 grams to milligrams (multiplying by .001??) Thanks

CHEM

What is the exact method/formula used to calculate oxidation state #'s? & how does one know when to use the correct oxidation state #? For example: Carbon carries 4,2,-4; Cl= 1,5,7,-1; and, Mn=2,3,4,7. Thanx. You use the seven rules in your text. Assigning of the oxidation ...

Chemistry

E=hv E=energy h= Planck's constant =6.626 x 10^-34 v= frequency 1. What is the energy of light having a frequency of 2.28 x 10^12? ( I do have an answer for this but I'm not so sure about it.) 2.What is the energy of light with a wavelength of 2.18 x 10^-5? 3. A photon of ...

Chemistry

H6P7: Young's Modulus Rank the following 3 classes of materials in order of increasing typical Young's Modulus: metals such as copper, plastics such as HDPE (high density polyethelene), and ceramics such as alumina (Al2O3). Do not look up the values of Young's Modulus, instead...

Chemistry

Thank you for your help. I did want to clarify why you are only calculating the Molar Mass for H2 and not the molar mass for H2O (or even H2O2). I'm not sure why you did this. Please clarify. See below: The following reaction represents the decomposition of hydrogen peroxide ...

chemistry

home / study / questions and answers / science / chemistry / a chemical engineer studying the properties of ... Question A chemical engineer studying the properties of fuels placed 1.760 g of a hydrocarbon in the bomb of a calorimeter and filled it with O2 gas The bomb was ...

VERY URGENT, HELP!

Consider a simple economy consisting of only four firms. Firm A, a mining enterprise, extracts iron ore. Firm B, a Steelmaker, produces steel sheets. Firm C, a carmaker, makes automobile while Firm D produces automobile tires. In 2016, firm A extracts 50,000 tons of ores, ...

Econ URGENT HELP!

Consider a simple economy consisting of only four firms. Firm A, a mining enterprise, extracts iron ore. Firm B, a Steelmaker, produces steel sheets. Firm C, a carmaker, makes automobile while Firm D produces automobile tires. In 2016, firm A extracts 50,000 tons of ores, ...

chemistry

I have two solutions of 0.1 Molar. A solution of magnesium chloride and a solution of potassium chloride. I thought that the 0.1 M solution of magnesium chloride would conduct electricity better than a 0.1 M solution of potassium chloride. I did a lab in my chemistry class but...

Chemistry

Hi Dr. Bob, this is a chemistry question. I don't know how to go about solving this problem: What is the pH of the solution created by combining 11.40 mL of the 0.10 M NaOH(aq)with 8.00 mL of the 0.10 M HC2H3O2(aq)? Here's what I have so far: (0.10M NaOH)(0.0114L)= 0.00114 mol...

Chemistry

I did a lab for Organic Chemistry I did a simple distillation for an unknown and found that it boiled at 76 degrees. I also found out that the unknown was ethanol since we knew what the 4 possibilities were and mine was closest to ethanol. I also did a fractional distillation ...

Chemistry

A cup of teat containing 400g of liquid at 20 degrees celsius was heated. If 58.5 kj of heat was absorbed by the tea, what would the final temperature be? Assume that the specific heat of the tea is the same as that of water (4.18). I am not sure how to start this problem. ...

Econ VERY URGENT, HELP!

Consider a simple economy consisting of only four firms. Firm A, a mining enterprise, extracts iron ore. Firm B, a Steelmaker, produces steel sheets. Firm C, a carmaker, makes automobile while Firm D produces automobile tires. In 2016, firm A extracts 50,000 tons of ores, ...

Chemistry

The term mole is used in chemistry to define an amount of a substance. For example, a mole of glucose, blood sugar, weighs 180.16 grams. A common concentration unit for solutions is moles of substance per liter of solution. We abbreviate this with the symbol M. For example, 0....

Majoooooor Help please please help me

Please can you give me what are the products , the colour of the flame, how does it react when : 1- Zinc reacting with oxygen Zinc reacting with air 2- Iron filings with oxygen Iron filings with air 3- Copper reacting with oxygen Copper reacting with air 4- Magnesuim reacting ...

Chemistry Lab

In chemistry we are doing a lab that involves crucibles and Mg ribbon, we have three days to complete the lab. Anyways do you think it would be alright to substitute the mass of the crucible we had the first day with the mass of the crucible we had today? We know how much the ...

Chemistry *DrBob222

Posted by Jamie on Sunday, June 20, 2010 at 3:36pm. You are given three test tubes that contain colourless liquid. One test tube contains benzene, another contains ethanol, and the third contains 2,4-hexadiene. Design a procedure that will tell you the contents of each test ...

Chemistry

I need serious help with 3 different chemistry problems: 1. If coal is assumed to be all carbon, carbon has a molecular weight of 12 lb-mass/lb-mol, and oxgyen (diatomic) has a molecular weight of 32 lb-mass/lb-mol, how much carbon dioxide (lb-mass/day) is produced in 171.4 lb...

Chemistry

Indicate how each of the following would affect the value of the absorbance (too high, too low, or not effect) of the indicated solution. I really need help. I do not understand these questions! This is from a chemistry activity to determine the unknown concentration of an ...

chemistry

I'm having trouble naming this organic chemistry compound. (I'm not sure how to include a picture in this, so I'll try my best to explain it in words and attempt to type it out) The full formula is C9H16. It's an alkyne and the longest carbon chain is 5 carbons long, so I know...

Chemistry II

What is the ^S for NaCl (l)?

MTI

what is chemistry

chemistry

what is a pi bond?

Chemistry

How do i solve [A]=[A]0 x e^-kt for k

chemistry

reinforcement??????????????????? help

Chemistry

What does "Kc" mean?

Chemistry

what is the pH of a 0.10 M NH3???

chemistry

what is the pH of a 0.10 M HC2H3O2

chemistry

How does pH = 8.75 give (H^+) = 1.77 x 10^-9.

chemistry

How does pH = 8.75 give (H^+) = 1.77 x 10^-9

science

chemistry help

chemistry

1000 mm = how many km

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