Saturday

April 19, 2014

April 19, 2014

Total # Posts: 185

**qualitative Chemistry**

specifically this is qualitative chem. The two compounds are metal halides and the common condition which the test is proceeded is in acidic condition. The most suitable reagent for that is dil nitric acid.

**chemistry**

I think its correct. lle is the least because it has the longest non polar R group, Ser has an OH the strongest polar group, His has NH group but are attached in ring which makes them least polar, Trp has 2 aromatic rings and Phe has 1 aromatic ring.

**chemistry**

first you need to draw a molecular orbital diagram. it is with the diagram that can help you identify bonding and antibonding electrons.

**chemistry**

both have different polarity. Polar substances can dissolve/mix with each other. non polar substances can dissolve/mix with each other. you cannot mix both polar and non polar substances. example: Oil is non polar and water is polar. you will find two distinct layers because o...

**chemistry**

Reaction: Na2CO3 + CuSO4 --> CuCO3 + Na2SO4 CuCO3 is insoluble and so form ppt. mole ratio: Na2CO3 : CuSO4 1 : 1 actual mole of CuSO4 = Mv = 0.159M x 26.7e-3L =_______moles = moles of Na2CO3. volume of Na2CO3 = n/M where n is the mole of Na2CO3 and M is the molarity of Na2C...

**Science-Chemistry**

a. a pencil and a book (totally different materials) b. this can be aldehyde and ketones c. salt and metal. they both conduct electricity though they have different structures.

**chemistry**

ok. matter is everything that surround us. anything that has mass, energy etc. liquid, solid, gases are all matters. even anything that moved having a velocity or kinetic energy or mass or even anything we can't see is matter. i recommend that you read more on cathode rays...

**Chemistry**

i guess log is 10g???...stp is standard temperature and pressure. in this condition, 1 mole of gas contains 22.4L. Is it propyrie or propyne??? whateva it is, its an organic compound so would yield H2O and CO2 when combusted completely. here's what you must do; construct a...

**Physics**

this is mostly physics. ensure to give the correct subject so that experts can come at your aid asap.

**chemistry**

Heat (Q) evolved is Q = mc?T where m is the mass in grams, c is the specific heat and ?T is the change in temperature. In this case, the change in temperature is in degreesCelcius and the energy is in calories. You can do conversion in the final answer to joules if you want us...

**Chemistry**

O2, Fe and Cl2 should all have zero enthalpy of formation because, they are pure or in diatomic state. However, Fe and Cl2 are not under standard conditions because standard condition is 25degreesC at 1atm. So to me it should be O2.

**Chemistry**

ok. You are confusing with the charge and the oxidation number. To me, both are the same, except that they are represented differently; the charge is written or shown in the chemical formula of the ion using a number followed by a sign (2- or 3- etc). The oxidation number show...

**CHEMISTRY**

ok..so write the balance equation; H2SO4 + 2NH3 --> (NH4)2SO4 this shows that 1 mole of sulphuric acid react with 2 moles of NH3 to produce 1mole of ammonium sulphate. The question asks the mass of (NH4)2SO4 produced by 5.00g of NH3 is used. So focus only on these two; igno...

**chemistry**

It looks like this is a practical/experiment type questions that you should already have your the results. It would be easier if you enter your values for the temperatures and pressures and leave the mole calculations and % for help.

**Chemistry**

To me its like this; the [OH] is 0.0025, so we can calculate [H] using [H][OH] = 1e14 and rearranging for [H] gives 1e14/[OH] with [H], we can find pH = -log[H]. Then use pH to find pOH using pH + pOH = 14. hope that helps.

**biology**

recall: human chromosome is represented as XX for females and XY for males. for hemophilic people, h is assigned next to the X chromosome (note, hemophilia is carried or present only on the X chromosome). Ok..the father of the woman (the mother of the boy) has hemophilia so ha...

**Chemistry**

67g of ice is 67/18 = 3.72moles. 6.0kJ/mol means it takes 6.0 kJ to convert 1mole of solid ice into liquid water. so, for 3.72moles requires 3.72x6= 22.333kJ energy input. the energy released is 445.1kJ/mol from NaOH. so 22.333kJ energy from NaOH must be used/provided..isn'...

**chemistry**

Break down the equation into reduction and oxidation half equation. oxidation reaction is I- --> IO3- balance the equation starting with oxygen by adding water, then followed by addition of H+ ions to balance H atoms, and then finally the electrons to balance the charges. Y...

**chemistry**

the balance equation is the overall net ionic equation. so use that to obtain the mole ratio between Na2Cr2O7 and KI. calculate the mole of sodium dichromate by m/Mr where m is 0.125g and Mr is molar mass. Then determine the mole of KI with using the mole of sodium dichromate ...

**chemistry**

I suggest you first do the dilution of the stock solution by a x10 in order to get 0.001M solution. 1. Pipette out 25mL of the stock solution into a 250mL v.flask, top up with water to the mark. 2. Top up to the mark with water using wash bottle or dropper. Your new solution s...

**Chemistry**

1. construct a balance equation for HCl and Zn reaction and note the mole ratio between HCl and Zn. 2. calculate the mass of Zn from the ore i.e. 36.0% of 7.55g gives the mass of Zinc. 3. Calculate the mole of zinc using n = m/Mr where Mr is the molar mass of zinc and m is the...

**Chemistry**

the desired molarity is 0.01M. The idea is to take a xgrams of sodium oxalate into a 500mL v.flask and dissolve it in water to make 0.01M solution. The xgrams is what you have to calculate. 1. calculate the moles of sodium oxalate using n = Mv where M is the molarity and v is ...

**Chemistry**

% yield = (exp.yield)/(theoretical) x 100% exp. yield = 2.81g to find theoretical yield; 1. Construct a balance equation for water electrolysed into H2 and O2. Note the mole ratio between H2O and H2. 2. calculate the mole of H2O using n = m/Mr where m is 80.5g and Mr is molar ...

**Chemistry**

1. balance equation is; Na2Cr2O7 + 2KI --> 2NaI + K2Cr2O7 mass of Na2Cr2O7 = 0.125g mole of Na2Cr2O7 = m/Mr = 0.125g/Mr =___mole mole ratio Na2Cr2O7 : KI 1 : 2 2.calculate the mole of KI using the mole ratio above and mole of Na2Cr2O7. volume of KI = n/M where n is the mole...

**chemistry**

2 moles of Al produces 2 moles of Fe. and 750grams of Al is 750g/26gmol-1 = 28.85moles. 2Al is 2x28.85moles = 57.7moles which is equal to the mole of Fe. with this mole, use the formula m = nMr to find the mass, where n is the mole and Mr is the molar mass of iron.

**d**

indicate your subject instead of just a d!!

**Chemistry 11**

try this; n = Mv = 0.6x1.2 = 0.72moles so, 0.72moles is the total mole i.e. KOH and water. Since the impure KOH is 84%, then the mole for KOH is; 0.84 x 0.72 = 0.605moles so, m = nMr = 0.605x(molar mass of KOH).

**Chemistry**

the equation simply shows that 2 moles of ammonium iodide reacts with 1 mole of Chlorine gas to produce 2 moles of ammonium chloride with 1 mole of Iodine. You can check for the phase for each chemical so it'll help you to understand more on the reaction. The equation you ...

**science**

molarity is the amount of solute dissolving in a liter of solute. H2O in the oxalic is simply water and so does not affect the molarity of the solution. The important part is the mass or mole of the pure oxalic acid. so, find the actual mass of the pure oxalic acid. 0.63g is t...

**Chemie**

the equilibrium constant is the ratio of the concentration product of the product and the reactant of a particular reaction. i.e. Kc = [NH4+]/[NH3][H+] where Kc is 4.5e8.

**Chemie**

incomplete??

**Chemistry**

incomplete??

**chemistry**

1.00g = 11100 cal how much grams in gallons???..how much joules in calories???...knowing these can lead you to your answer...

**Chemistry**

Q=mc?T where ?T is the change in temperature in degrees, m is the mass in grams and c is the specific heat capacity of water.

**chem 5**

use avogadros number 1mole = 6.02e23 atoms how many moles are there in 2.5x10e21 atoms???

**organic chem**

the % given is a % by mass. so they are grams. convert the mass to mole for each element divide each mole with the smallest mole round off the moles to 1 sig figure. then you can name them. the empirical formula is C3H6O. this formula can be an aldehyde and a ketone.

**chemistry**

HCl is a limiting agent sing Mg is excess. so the amount of H2 gas depend on the amount of HCl. 2 moles HCl produces 1 mole H2 calculate the mole of HCl; mole = cv = 3.0x0.075 = 0.225moles so mole of H2 is half of 0.225 = 0.1125mole. At STP, 1mole of any gas contains 22.4L of ...

**science**

3 moles of O2 is produced. use avogadros number 6.02e23 molecules in 1 mole. 1mole = 6.02e23 molecules of O2. how many molecules are present in 3 moles of O2??

**Chemistry**

the carbon should contain 4 bonds. so CH3COCH3 means that the middle carbon is double bonded to oxygen to make 4 bonds (one bond to each CH3 and double bonded to Oxygen). In ether, the Carbon is single bonded to the oxygen, which will have something like CH3CH2OCH3. for alkyne...

**Physical Science**

stream of particles

**Chemistry**

that depends on the number of moles of the acids that need to be neutralized by the base and the concentration of the base. 1. HNO2 + NaOH --> NaNO2 + H2O i.e. 1 mole base react with 1 mole acid the mole for the HNO2 is cv = 0.1Mx0.025L = 0.0025mol = mole of NaOH therefore,...

**Chemistry**

Yes you mistake in identifying the main chain. the main chain is the longest chain, i.e. from the left CH3 to the bottom CH3 which contains 7 carbons i.e. heptane. so, branch CH3 and CH2CH3 are on carbon 4 (4-ethyl-4methyl)....

**Chemistry**

2,2 dimethyl means two CH3 branches attached to the second carbon of the parent chain. 2-ethyl means the -CH2CH3 chain attached to the second carbon of the parent chain. the parent chain is the longest chain. the longest chain in the formula you gave consisted of 4 carbons i.e...

**Chemistry**

yes there are butyl, pentyl and so on. these are called alkyl groups or side chains. they only be side chains if they are attached to the longer carbon skeleton.

**Chemistry**

prioritize the longest chain as the parent/root. so the chain on the right has 3 carbons (propane). the other two are shortest and so they are branches.

**chemistry**

NaCl solubility at 100degrees is 39.1g/100mL. so you can use this to calculate how much will dissolve in 750mL of water.

**chemistry**

ensure the equation is balanced. obtain the mole ratio between Zn and Ag i.e. 1 mole of Zn produces 2 moles of Ag convert the mass of Ag (m=5.4g) into mole using m/Mr where Mr is the molar mass of Ag. take note of that mole for Ag and use it to calculate the mole for Zn, using...

**chemistry**

the energy of the photon is hc/lamda where h is the Planck's constant, c is the speed of light and lamda is the wavelength in meters.

**Chemistry**

ppm is mg/L so 1.08e3ppm is 1.083e3mg/L. you can convert this to mole/L by simply converting the mg to grams then to mole using m/Mr where m is the mass in grams and Mr is the molar mass of Na (periodic table). once you get that, you will end up with a mol/L. Then you need to ...

**chemistry**

molarity is mol/L i.e. how much mole of solute dissolving in 1 L of the solvent. calculated using C = n/V where n is the mole and V is the volume in L. solute is NaCl solvent is water find the mole of NaCl using m/Mr where m is the mass in grams and Mr is the molar mass in g/m...

**Physical science**

acceleration is change in velocity over change in time: ?v/?t where ?v is change in velocity and ?t is change in time in seconds. the change in velocity is the difference between the final and initial velocities i.e. from rest to 10. If 10 is in m/s, then ?v = final velocity -...

**Chemistry**

yes

**Chemistry**

it is an ionic compound so how about using electrolysis???...

**chemistry**

calculate the mole of HCl using m/Mr calculate the mole for water using the same formula add to two moles to get the total mole of the solution. divide the mole of HCl by the total mole to get your mole fraction.

**chemistry**

the solute is the HCl because it dissolved in water (a solvent). we have the mass so we can calculate the mole using m/Mr. the mole of water is also m/Mr the mole fraction is the mole of the solute divided by the total mole of the solution.

**Chemistry**

the cathode is the site of reduction..but you should check your equation: Note that reduction can be characterized by the gaining of electrons.

**Chemistry**

the question says 'for the following equations????...where are the equations??..i can't see any equations.. anyway..the first one is calcium carbonate???? so the ionic equation for its formation is; Ca2+ + CO32- --> CaCO3 whereas Fe(SCN)2+ is; Fe3+ + SCN- --> Fe(...

**Chemistry**

incomplete????

**science**

amu is atomic mass unit or the proportion of the isotope existing in nature expressed in percentage. i.e. 6Li exist approximately 6.015% while 7Li exist 7.016%. hope that helps.

**science**

this is tricky. In my opinion, two object moving at the same and opposite direction means that both object traveled from a different point of origin. So if we have these objects stuck together because of the constant d, then i guess neither of the object will make it to the in...

**science**

first assign the chemicals into their chemical formula; Ferrous sulphate is FeSO4 Sodium hydroxide is NaOH Ferrous hydroxide is Fe(OH)2 Sodium sulphate is Na2SO4 hope that helps

**chemistry**

1. convert the masses to the mole using the molar mass; n(B) = m/Mr = 6.444g/10gmol-1 = 0.6444mol n(H) = m/Mr = 1.803g/1gmol-1 = 1.803mol divide the moles by the smallest mole; 0.6444/0.6444 = 1 B 1.803/0.6444 = 2.79 H Use the whole number as we are to find the empirical formu...

**Chemistry**

find the mole for HNO3 using n = MV where M is the molarity and V is the volume in Liters. then use the balance equation; KOH + HNO3 --> KNO3 + H2O the reaction is 1:1 so the mole you calculated for HNO3 is also the mole for KOH. i.e. mole KOH = mole HNO3. then convert the ...

**Chemistry**

n1 = cv = 0.1x0.25 = 0.025mol n2 = cv = 0.5x0.3 = 0.15mol so the total mole after mixing is; 0.025+0.15 = 0.175mole and the total volume is; 250+300 = 550mL = 0.55L thus the concentration is; total mole/total volume = 0.175mol/0.55L = 0.32mol/L hope that helps...

**Chemistry**

the total pressure will be the sum of the partial pressure of all the gases at equilibrium.

**Chemistry**

try this; % yield = (exp. yield)/(theoretical yield) x100% where exp. yield is the experimental yield (what you actually get) theoretical yield is calculated from the equation using the mass of NH3 to determine the mass of NO. hope that helps

**Chemistry**

% yield = (experimental yield/theoretical yield) x 100% experimental yield is the mass obtained during electrolysis. to determine the theoretical yield, you have to find the limiting agent from the balanced equation, then use its mole to determine the mole for Chlorine. Then c...

**algebra**

have you try using a ratio?? 225miles : 10 gallons 279miles : x gallons

**Chemistry**

part per million (ppm) is mg/L. so 5.53ppm is 5.53mg/L of CaCO3. convert the concentration to Molarity (mol/L); 5.53mg = 5.53e-3g mole in 5.53e-3g = m/Mr = 5.53e-3g/48gmol-1 = 1.152e-4mol i.e. approximately 0.00012mol/L CaCO3. to find the mole in 615mL, we multiply the molarit...

**Science**

% by weight (w/v) is 100g/100mL. so 0.01% means 10g/100mL or 100g/1L. am not sure what the question is asking!!!

**biology**

already you have the hints; i.e. water, proteins and nucleic acids. these are the most fundamental of life without these life is not possible. water contains one oxygen atom and 2 hydrogen atoms in a covalent bond. because of the difference in the atoms electronegativity (oxyg...

**chemistry**

find the mole for each and then determine the number of particles for each using the avogadros number; 1mole = 6.02e23 particles.

**Chemistry**

what's the ¡Ñ???..unless it don't matter, then just convert the mL to liters such that; 240mL becomes 0.24L. using the convention 1mole = 22.4L, find the mole for the 0.24L. i.e. 0.24L/22.4 = 1.07e-2moles. using avogadros number; 1mole = 6.02e23 atoms i.e....

**physics**

if the * is the degrees, then you need to draw the vectors according to their direction. you can use a graph paper and make your own scale: say one unit cube is 10km/hr. then use the protractor to draw the vectors taking an horizontal line as zero degrees. then draw the vector...

**addition Chemistry**

the enthalpy -414kJ/mol is the enthalpy of combustion. i.e. how much energy released for one mole of Na metal to burn in air. so the actual equation is; Na + 1/2O2 --> NaO ?H = -414kJ/mol. However, the equation given in your question is written in whole number coefficients ...

**Science**

potential energy is mgh = m(9.8)(9) = 88.2m where m is the mass of the apple. given that there is no air resistance, all of these potential energy is converted to kinetic energy during the fall i.e. Ep = Ek so, Ek = 1/2mv^2 = Ep 1/2mv^2 = 88.2m v^2 = 88.2m/0.5m ...so you can s...

**Biology**

try tree, grass and algae...

**chemistry**

it should have the same pattern; i.e. form diatomic molecules as by the other halogens. Molecules with more molecular weight have higher melting and boiling points due to the increase in electron density, which induces the magnitude of the dipole-dipole attraction.

**Biology**

the idea is to take out the exact volume from the stock solution and dilute it with water to make up 10mL total volume giving the concentration needed. before commencing, ensure that you transfer sufficient volume of the stock solution into a 100mL beaker to use. Method 1: If ...

**Chemistry**

the reaction is: 2HNO3 + Ca(OH)2 --> Ca(NO3)2 + 2H2O we know the mole of calcium hydroxide n=cv = 4.2mol/L x 0.025L = _____ this mole needs to be neutralized by the acid. so we need to calculate the mole of nitric acid using the mole ratio from the balanced equation; 2 mole...

**Chemistry**

the ratio of isotopes are measured from their relative masses or abundance of the elements. so, the equipment is called an isotope-ratio mass spectroscopy.

**Chemistry**

use the convention; 22.4L = 1.00moles so convert that volume of argon in neon sign to liters and fine the mole for that volume using the above convention. then use this; 1 mole = 6.02e23 atoms to find the number of atoms in the mole you calculated above.

**science**

use the heat of vaporization 1gram = 540calories how many calories when 500g is vaporized?

**chemistry**

iron oxide and hydrogen gas are produced.

**Chemistry**

density is mass/volume. be careful with the unit.

**Chemistry**

1.mole of NaOH added = cv = 0.365x15e-3 = 5.48e-3 moles. Reaction; HI + NaOH --> NaI + H2O pH = -log[H+] the [H+] is the concentration of the acid as 15ml NaOH has been added. the equation states that, 1 mole of NaOH neutralize 1 mole of HI. So, after adding 15ml, we introd...

**addition Chemistry**

in order for the hydrogen bond to form in a molecule, the molecule must have an hydrogen atom attached to either oxygen, nitrogen or fluorine. so, the oxygen in C=O bond is not attached to hydrogen and so can't form hydrogen bond.

**chemistry**

moles = mass/Molar mass the mass is given and the molar mass can be obtained from the periodic table.

**Chemistry**

first find the limiting agent because this determines the amount of water produced. this is done by calculating the mole of each gas and see which has a mole that satisfy the reaction; for hydrogen; 7.30/2 = 3.65moles for oxygen; 7.30/32 = 0.228moles so hydrogen is excess in a...

**chemestry**

water has 2 lone pairs and 2 surrounding atoms oxygen gas has 2 lone pairs on each atom bonded in a double bond 1 lone pair on nitrogen bonded (single) to 3 hydrogen atoms nitrogen is bonded to 4 hydrogen atoms, and it should have a positive charge.

**chemistry**

convert calories to joules. take note of the delta H for its sign.

**Chemistry 101**

is this Chemistry??? by the way, apply the normal rule for the volume i.e. Length x width x height

**Chemistry**

the alkane is saturated i.e. the carbon bonds to 4 atoms. It contains only single bonds and contains no functional group. The alkene has a double bond between two of the carbon atoms. this double bond makes the alkene unsaturated and so determines the reactivity of the alkene ...

**Science**

the question does not make sense..the resultant vector is always longer than the two vectors because it is formed by the 90degrees intersection of the smaller forces!!!..so how come the resultant vector form a 90degree with another smaller vector??? the smaller vectors should ...

**chemistry**

KE = 1/2mv^2 and v = sqrt[(2KE)/m] and momentum = mv = (m)x[sqrt(2KE)/m] = msqrt[(2KE)/m] where KE is the bond energy in kJ/bond.

**Chemistry**

right i forgot the *100

**Chemistry**

total mass of the solution is 400+80 = 480g. mass% of solute = mass of solute/total mass of solution hope that helps...

**Chemistry**

@ bobpursley..your equation is incorrect so i came up with this one...

**Chemistry**

the question is based on the decomposition of calcium carbonate through heating; CaCO3(s) --> CaO(s) + CO2(g) 50 grams of calcium oxide is 0.893moles. the theoretical mole is 1:1 between caCO3 and CaO, so 0.893moles of CaCO3 is needed. mass of CaCO3 = moles of CaCO3 x Molar...

**Chemistry**

1. the solution is diluted by 5/475 dilution factor i.e. 1/95x so you can also use this factor to find the initial molarity (M1) by dividing the final molarity (0.1M) with 1/95..i.e. 0.1x95 = 9.5M. 2. c1v1=c2v2 and we are looking for v2 so; v2=(c1v1)/c2 = (7x16)/2.5 = 44.8mL i...