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Questions44

• improper integral?

integral from 6 to 8

4 / (x-6)^3 dx

integral from infinite to 0

e^2 / e^(2x) + 3 dx

• definite integral using the substitution rule?

if f is continuous and integral from 9 to 0 f(x) dx=4

find integral 3 to 0 xf(x^2) dx

• indefinite integral question?

USe the substitution rule

x divided by squareroot of x^2 +1

what would be the indefinite integral of that ? use substitution rule. thankx

• How many possible four aminoacid long peptides (a peptide is a small protein) can be made from the below pepti

How many possible four aminoacid long peptides (a peptide is a small protein) can be made from the below peptides.

(I.E. rearrange them to form different sequences, where each sequence is made up of only the four aminoacids given below)

met trp met trp

Enter a whole number numerical answer.

• Which of the following statements are true for the reactions that precede them.?

Which of the following statements are true for the reactions that precede them.

NOTE: Read the equations left to right

a) NH3 + H2O ↔ NH4 + + OH − NH3 is the Lewis base

b) HF + H2O ↔ H3O + + F &minus Water is the Lewis acid

c) C5H5N + H2O ↔ C5H5NH + + OH &minus Water is the Lewis base

d) Al(H2O)6 3+ + H2O ↔ H3O + + Al(H2O)5OH 2+ Al(H2O)6 3+ is the Lewis acid

e) NH4 + + H2O ↔ H3O + + NH3 Water is the Lewis acid

• calculate the percent yield?

For the reaction BaI2 + MgSO4 (aq) BaSO4 precipitates out.

Calculate the percent yield (%) if 18.052 g of BaSO4 precipitates

when 1.950 L of 0.0550 M BaI2 and 2.100 L of 0.0426 M MgSO4 (aq) are mixed.

CuCl2

• optical isomers?

WHAT MAKES A chemical structure..optical isomer?!?!?!?!?!?! how do you count how many there are?!?! please tell me I need to know! thanx!

• isomers and isomerism?

Which of the following are true statemtents about isomers/isomerization ?

a) Looking at a pair of Optical isomers one would see the same

chemical bonds, however these bonds would have different spatial arrangements in each isomer

b) Optical isomers always have identical chemical properties

c) A thumbtack and its mirror image are identical, they are superimposable

d) The mirror image of your left hand appears the same as your left hand, i.e. superimposable

• exceptions to the octet rule?

Which of the following compounds present exceptions to the octet rule ?

a) PF5

b) XeF4O

c) XeF6

d) ClO3-

e) BrF3

NOTE: condsider formal charges when drawing Lewis structures

• resonance structure?

Choose those statements that are true for the most stable resonance structure of the molecules H−C−N and C−N−H

a) Both of these structures have a triple bond between the carbon and nitrogen atoms

b) Both of these structures have a positive charge on the nitrogen atom

c) CNH is predicted to be more stable than HCN

d) One resonance structure has eight valence electrons and the other has ten valence electrons

e) These two resonance structures are resonance structures of different molecules

• Resonance structures..chemistry help plz?

Choose those statements that are true for the most stable resonance structure of the molecules H−C−N and C−N−H

a) Both of these structures have a triple bond between the carbon and nitrogen atoms

b) Both of these structures have a positive charge on the nitrogen atom

c) CNH is predicted to be more stable than HCN

d) One resonance structure has eight valence electrons and the other has ten valence electrons

e) These two resonance structures are resonance structures of different molecules

• chemistry- energy change PLZZZZ HELp!?

calculate the energy change in kJ for the formation of 0.25 mol of NaI(s)

given the following information: I2(s) ? I2(g) : 62.44 KJ/mol

Na(s) ? Na(g) : 107.32 KJ/mol

I2(g) ? 2I(g) : 276.10 KJ/mol

Na+(g) + e- ? Na(g) : -496 KJ/mol

Electron affinity for I(g) : -295.16 KJ/mol

Lattice energy for NaI = -702 KJ/mol

• help meee! chemistry! experts help!?

Using average bond energy values estimate ?H for the following gas phase reaction.

2CH2=CHCH3 + 2NH3 + 3O2 produces-> 2CH2=CHCN + 6H2O

please tell me how u arrived at htat answer.i've tried sO many times i keep getting it wrong! thanx!

• bond energy and energy related chemistry question?

Using average bond energy values estimate ?H for the following gas phase reaction.

2CH2=CHCH3 + 2NH3 + 3O2 ? 2CH2=CHCN + 6H2O

ANOTHER QUESTION:

Calculate the energy change in kJ for the formation of 0.25 mol of NaI(s)

given the following information: I2(s) ? I2(g) : 62.44 KJ/mol

Na(s) ? Na(g) : 107.32 KJ/mol

I2(g) ? 2I(g) : 276.10 KJ/mol

Na+(g) + e- ? Na(g) : -496 KJ/mol

Electron affinity for I(g) : -295.16 KJ/mol

Lattice energy for NaI = -702 KJ/mol

Enter a numerical answer only, do not enter units.

im jsut stuck on these two. please explain how u got the answer. thanx! it'll be great help!

• chesmitry sis and trans isomers. EXPERTS PLEASE?

Which of the following compounds can exist as cis and trans isomers ?

a) CH2=CHF

b) CHCl=CH-CH2Cl

c) HClCFCl

d) CBrBr=CH-CH2Cl

e) 3-hexene

please explain how uk now when something is both cis and trans isomer. thanx.

(H-C=N-H)+ with two electrons on top of N...like two dots on top of N.

Choose the statements that are true about the proposed Lewis structure shown above for the molecule [HCNH]+.

a) For this Lewis structure the number of valence electrons shown is correct

b) All of the atoms have an octet of electrons

c) In this Lewis structure the formal positive charge is on the carbon atom

d) This is the best Lewis structure for the molecule [HCNH]+

• cheMISTRY!?

Which of the following compounds can exist as cis and trans isomers ?

a) CH2=CHF

b) CHCl=CH-CH2Cl

c) HClCFCl

d) CBrBr=CH-CH2Cl

e) 3-hexene

please explain how uk now when something is both cis and trans isomer. thanx.