CHM

138 results

advanced biology

chemical properties describe how a _____ changes into a new substance. This site will give you a definition and examples. http://www.elmhurst.edu/~chm/vchembook/105Achemprop.html

CHM 152

At 20oC, a 2.32 M aqueous solution of Ammonium Chloride has a density of 1.0344g/ml. WHat is the molality of Ammonium Chloride in the solution? The formula weight of NH4Cl is 53.50 g/mol?? I am not sure how to incorporate the density into the problem to come up with how to ...

science

What is carbon cycling? http://www.elmhurst.edu/~chm/vchembook/306carbon.html A thing made out of carbon. It is in a shape like a circle.

chemistry

hi, I am wondering if benzyl acetate is polar or nonpolar? because it has a non polar benzene ring but also it has the ester bit attached so i am confused. Also i cant seem to understand the vander waal forces that are in it. if anybody could help that would be super A little ...

CHM 300

if the pKa of HCN is 9.21,what it its Ka?

CHM

Why it is OK to prepare the titrant solution so inaccurately?

CHM

what is meant by the term "free calcium"?

CHM 157

calculate the lattice energy of CaO

chm

determing concentration by spectroscopy lab discussion?

CHM

How to balance the following equation: Na(s) + H2O(l) yields?

chm

how does CO2 affect the titer of a solution of NaOH ?

chm

I need to find the mass of 0.0225 mole of NH3?

Analytical CHM Lab

why is NaOH a poor primary standard ?

chm

The molar solubility of PbBr2 at 250C is 1.0x10^-2. Calculate the Ksp.

CHM

Calculate the solubility of Cu(oh)2 in grams per liters of solution if Ksp for Cu(OH)2 IS 4.8X 10^-20

org chm

how many grams of KOH are needed to make 590 ml of a solution with a pH of 11.35?

chm

How many valence shell electrons would you expect for an S2- ion? 8 Am I correct.

ChM

Calculate the pressure exerted by 1.2 mol of gas in a volume of 28.2 L and at a temperature of 61 C.

CHM 300

Explain why I2 is not a good primary standard? why is this an iodometric procedure?

chm

What is the theoretical yield of iron if we begin the reaction with 10.5g of AL (assume an excess of Fe2)3)

Organic CHM II

Define the following sets of term: α- and β- notation

Analytical CHM 300

which rating system gives the analyst the most information?

ANALYTICAL CHM

Describe the correct technique for reading the meniscus of a solution in the buret.

CHM 300

What explains the difference between the propagated uncertainty and the standard deviation?

CHM

How might chromophores, auxochromes, and solubilizing groups be responsible for the position of dyes on a chromatogram?

CHM

In the chemical formula of ammonium sulfate, (NH4)2SO4, how many hydrogen atoms are present? 4

Organic CHM II

What are the most important monosaccarides in biological systems? glucose and fructose?? is that correct?

chm

Calculate the theoretical amounts of 0.1000 M NaOH titrant used to titrate 0.8 and 0.9 g KHP

CHM

Calculate the theoretical amounts of 0.1000 M NaOH titrant used to titrate 0.8 and 0.9 g KHP

CHM

what other compounds may be present at the trace level that would interfere with this titration? (EDTA)

chm

KBr does not dissolve in nonpolar solvents because.... I think it is because they have similar solute but I really don't know.

CHM

If 12.0 ml of a 0.050M sodium acetate is added to 22.0ml of water, what is the final concentration of the NaC2H3O2?

CHM 152

How many gram of Fe+3 are required to make 1.0 L of an aqueous solution of 10 ppm Fe+3? Assume density of water is 1.00 g/mL.

chm

If 0.0490g of AgIO3 DISOLVES per liter of solution, calculate the solubility product constant.

CHM

Calculate the percent ionization of hydrazoic acid (HN3) in solutions of each of the following concentrations A) 0.377 M B) 0.107 M C) 4.16*10^-2 M Ka= 1.9*10^-5

CHM

suggest an alternative indicator for the standardization reaction. Explain the rationale behind your choice. Used 10 g of KHP

chemistry

did i answer the question: Explain how one of the major concepts learned in CHM 111 applies to everyday life. One major concept that was learned in CHM 111 that applies to everyday life is stoichiometry. Stoichiometry is founded on the law of conservation of mass where the ...

CHM

we will do a project on this topic ;HPLC with fluorescence detection to quantify the amounts of various preservatives in several kinds of soda. so what can be analyzed ?

ap chemistry

did i answer the question: Explain how one of the major concepts learned in CHM 111 applies to everyday life. One major concept that was learned in CHM 111 that applies to everyday life is stoichiometry. Stoichiometry is founded on the law of conservation of mass where the ...

CHM

Which of the following is not an example of a physical change? is this the right Answer accidentally leaving a piece of toast in the toaster until it is completely black

chm 112

Only 6M KOH was present on the reagent shelf- there was no 6M NaOH. explain what effect this substitution has on the test for the presence of the ammonium ion?

Chm

If we increased the amount of acetic acid and sodium bicarbonate to 2.0 moles, what effect would this have on the reaction? The enthalpy change? Explain

chm

If a neutral element has 8 neutrons and 7 electrons, which expression correctly identifies the element?

CHM

How many liters in volume are occupied by 250 liters of bromine at STP?

chm

What is the pH of the solution obtained by mixing 30.00mL OF 0.250M HCL AND 30.00mL OF 0.125M NaOH?

ANALYTICAL CHM

What are the possible sources of error in using a graduated pipet? in using a buret?

analytical chm

Analytical Balance which weighing method does one use when drying constant weight? Why?

Chm 203

On a size exclusion separation column (e.g. Sephadex) would you expect the longer or shorter chain length compound to be eluted first? Why? Explain? Thanx!

CHM 152

For the system 2A (g) + B( g) = 2C (g), if the initial concentration of pure C is 1.00 M, the equilibrium concentration is 0.40 M. What is the value of Kc? Choose one answer. a. 5.0 b. 0.45 c. 0.67 d. 2.2 e. 1.5

Chm

What is the molarity of a saturated solution of potassium sulfate if the solubility is 13 g per 100 g H2O at 25°C? The density of the solution is 1.1 g/mL

CHM LAB

we are doing complexometric titration for the data sheet it askes to find mass of CaCO3 in sample how do I find it ?

CHM 1020

Calculate the amount of heat required to raise the temperature of a 39 g sample of water from 9 ∘C to 21 ∘C

CHM 1020

alculate the amount of heat required to raise the temperature of a 39 g sample of water from 9 ∘C to 21 ∘C

chm

Which of the following is a covalent compound composed of nonpolar covalent bonds? Answer >>H2 H2O CF4 CH4 NaF

chm

An aqueous solution that is 30.0 percent sulfuric acid (H2SO4) by mass has a density of 1.105 g/mL. Determine the molarity of the solution.

CHM

Calculate the molecular weight of a small protein if a 0.32 g sample dissolved in 161 mL of H2O has an osmotic pressure of 9.0 mmHg at 25 degree celcius. (R=0.0821 L X atm/K X mol)

CHM 152

A 0.750 L bottle of a French Merlot is said to contain 12.5% alcohol by volume. How much of the liquid, in mL, in the bottle is water?

CHM formula needed, pls?

How many milliliters of a 0.25 M sucrose solution contain 2.0 grams? The molar mass of sucrose (C12H22O11 ) is 342.3 g/mol.

Analytical CHM

Chemical Reagent: Iodine (resublimed crystals Lot# 127287) What is the numerical health hazard for this reagent? Explain what this means

chm

An aqueous solution that is 10.0 percent sulfuric acid (H2SO4) by mass has a density of 1.143 g/mL. Determine the molality of the solution. ( 3 significant figures)

chm

An aqueous solution that is 10.0 percent sulfuric acid (H2SO4) by mass has a density of 1.143 g/mL. Determine the molality of the solution. ( 3 significant figures)

Analytical CHM Lab

Chemical reagent: Iodine (resublimed crystals lot# 127287) What is the numerical fire hazard for this reagent?Explain what this means

CHM

Predict whether the following bonds are ionic, covalent, or polar covalent based on the bonding atoms electronegativities: N2 The Al-O bond in Al2O3 MgO CuS

CHM

Consider the following reaction: HCN <--> H+ + CN- delta H = 315kJ If 1.00 mole of CN- in the form of NaCN was added to equilibrium mixture, describe the effect on [H+], [HCN], [CN-], pH, and heat.

CHM

How many milliliters of a 0.25 M sucrose solution contain 2.0 grams? The molar mass of sucrose (C12H22O11 ) is 342.3 g/mol. Need the formula to understand how to continue with more problems.

Chm

8.08g of KNO3 were required to saturate 25g of distilled water at 20oC. Calculate the solubility of the solute in a) g/dm^3 of water b) mol/dm^3 of water

Organic CHM II

With what starting material are all lipids are built? Describe the process that a long carbon chain is rearranged into a multi-cyclic molecule that is basis for steroids? Please explain in detail

chm

An unknown radioactive substance has a half-life of 3.20 . If 34.8 of the substance is currently present, what mass was present 8.00 hours ago?

CHM Lab

How much titrant will be required if your EDTA titrant is exactly 0.01 M and you weighed out exactly 0.4 g calcium carbonate?

chm

At a certain temperature the concentration of was 0.400 and that of was 0.235 . At equilibrium the concentration of was found to be 0.250 . What is the value of at this temperature?

CHM

How much titrant will be required if your EDTA titrant is exactly 0.01 M and you weighed out exactly 0.4 g calcium carbonate?

chm

Calculate the PH OF A SOLUTION prepared by mixing 15.0mL OF 0.50 M OF NaOH AND 30.0mL OF 0.50 M BENZOIC ACID SOLUTION?( Benzoicacid is monoprotic and its dissociation constant is 6.5*10^-5)

Analytical CHM

Rank the following items in order of accuracy: volumetric pipet, beaker,buret,erlenmeyer flask,volumetric flask

Organic CHM Lab

a) what is meant by the term flooding of the fractionating column and what causes it? b) Assume that no azeotropes are formed, would it be easier to separate n-hexane and benzene or n-hexane and toluene by distillation? expalin? Thank you!

Chm Help Please!!!

What is the boiling point of a solution of benzene contain 0.2 moles of a non volatile solute in 125 grams of benzene given that pure benzene has a b.p. of 80.1 Celcius and a Kbp of +2.53 C/m. Thanks!

CHM 300

We did experiment: Spectrophotometry(Determination of iron with 1,10-Phenanthroline) It asks me to find the molar absorptivity of the Fe-phenanthroline complex? How do i find it ? please eplain.

ionic compounds!

why are ionic compounds abundant in nature? Betty, I don't know how to answer your question. Abundant compared to what? How is abundant defined? I would think there are more covalent compounds in nature than ionic compounds but I may be wrong. Can you clarify the question a ...

chm

gunpowder is a mixture of potassium nitrate , sulfur and carbon in th proportion (by mass) of 6:1:1 (KNO3;S:C). A typical riflr shell contains 3.2 gunpowder. How many moles of each compnent are there in our sample gunpowder?

Chm Help Please!!!

you wish to purify by distillation a material that has a boiling point of 205 C and reacts with air but this material will decompose if heated above 150 C. How would you set up the system to distill this material? Thanks!

CHM

From the following: 1) pure water 2) 0.01 m solution of table sugar (C12H22O11) 3) 0.01 m solution of NaCl 4) 0.01 m solution of CaCl2 Choose the one with the largest van't Hoff factor and hence the lowest freezing point.

CHM 152

The freezing point of an aqueous solution of glucose was measured to be -1.52 oC. What is the osmotic pressure, in atm, of 100 mL of this solution at 25.0 oC? (Kf = 1.86 oC/m) When I calculated it out I got 16.79 atm but the answer was wrong don't know what I messed up on.

Chm General 2

if a student doing an experiment failed to dry the KHP before using it to standarize the NaOH solution. A) Would her calculated molarity of the NaOH solution probably be too hight or too Low?

Chm 2046

The normal boiling point of liquid ethanol is 351 K. Assuming that its molar heat of vaporization is constant at 37.5 kJ/mol, the boiling point of C2H5OH when the external pressure is 1.35 atm is K.

chm

How would you classify the following material?swimming pool water homogeneous mixture<<< heterogeneous mixture a pure element a pure compound depends on how many children have been in it

CHM 1010

Under pressure of 862kPa, a gas has a volume of 752ml. The pressure is increased, without changing the temperature, until the volume is 624ml. What is the new pressure

chm

The Lewis dot structure of ammonia, NH3, reveals that it has one lone pair of electrons and three bonds (each to a hydrogen) around the central nitrogen atom. According to VSEPR theory, what molecular shape will it have? i thought it was tetrahedral but its wrong. what and why...

chm

Silver chloride, often used in silver plating, contains 75.27% .Calculate the mass of silver chloride required to plate 195 of pure silver.

CHM 152

An automobile antifreeze contains equal volumes of ethylene glycol (d=1.114 g/mL and FW = 62.07) and water (d=1.00 g/mL) at 25oC. The solution has a density of 1.06 g/mL. What is the molarity of ethylene glycol in the solution?

CHM

Assuming the density of acetic acid solution is 1.0 g/mL, determine the volume of the acetic acid solution necessary to neutralize 25.0 mL of 0.10 M NaOH. Record this calculation on your report sheet

chm

what is ph of a solution made by mixing 55ml of 0.12M in Formaic acid and 65ml of 0.12M of Sodium Foramte? For Ka of Formaic acid is 1.4x10^-4

CHM 105

Vinegar contains ethanoic acid (CH3OOH).titration of 3.00g of vinegar with 0.12M NAOH Solution requires 23.0cm3 to reach the equivalent ppoint.what is the weight percentage of the ethanioc acid in vinegar?

CHM

Some of the cyclohexane solvent vaporized during the temperature versus time measurement. Will this loss of cyclohexane result in its freezing point being recorded as too high, too low or unaffected? Explain. Please someone explain this to me I don't understand it...Thank you

Gen Chm 2

What determines the greatest buffer capacity when looking at solutions? The professor said he would have a list of solutions on the test and we choose the one with the best buffer capacity.

CHM 152

The activation energy for a reaction is 37.6 kJ/mole. The rate constant for the reaction is 5.4 x 10-3 s-1 at 45 oC, Calculate the rate constant at 145 oC.

chm 2

On the same type of problem as the previous one, it is now asking the pH of 1ml of NaOH plus 50ml water. If i solve for pOH taking .001ml / .051, i get the same number as before, can i just subtract the number from 14 to get pH of the basic solution? 12.29 was what i came up ...

CHM 300

Experiment: Redox titration;determination of ascorbic acid by an iodometric back-titration Why is sodium carbonate added to the thiosulfate solution ? why is the water used for preparing the thiosulfate solution boiled ?

biology

What forms of energy are involved in metabolism? Since this is not my area of expertise, I searched Google under the key words "metabolism energy" to get these possible sources: http://www.elmhurst.edu/~chm/vchembook/5900verviewmet.html http://ds9a.nl/metabolism/ http://staff....

chm

The specific heat of fat is 0.45 cal/(g) , and the density of fat is 0.94 g/cm^3 . How much energy (in calories) is needed to heat 22 cm^3 of fat from room temperature (25 ^\circ {\rm C}) to its melting point (35 ^\circ {\rm C})?

CHM 312L

Experiment: Thermodynamics of Real Gases Chemistry 311L (Heat Capacity Ratio and the Joule-Thomson Effect) question: Imagine that you forget that an oil manometer measures pressures above atmospheric. What will happen to your calculated heat capacity ratios, and why?

chm

The mass of Oceanis 1.8*10 to 21 kg.The ocean contains 1.076%sodium ion,Na+what is mass of sodium in ocean

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