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3 years ago

What is the amount of heat released when 25g of water cools 12.5 degrees C ?

1 answer:

4 0

Water can't cool at a single temperature. It must start at a higher temperature, and drop to a lower temperature in order to cool. Unless we know the other temperature, there is no way to calculate the amount of thermal energy released.

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Determine if each of the following statements about chiral molecules is True or False and select the best answer from the dropdo

oee [108]

Answer:

See explanation

Explanation:

-) True or False: All R stereocenters are dextrorotatory.

The absolute configuration is based is in specific rules that are not related to the ability to deflect polarized light. FALSE

-) True or False: Chiral centers in organic molecules will have 4 different groups attached to a carbon.

A chiral carbon by definition is a carbon with 4 groups. TRUE

-) True or False: A racemic mixture has an optical activity of 0.

In a racemic mixture, we have equal amounts of enantiomers, and this cancels out the optical activity. TRUE

-) True or False: Normal linear amines can be chiral centers.

In primary amines, we have 2 hydrogens. Therefore all the groups can not be different. So, is TRUE

-)True or False: Compound C has an optical activity of 0.

We need to know the structure of the compound

-)True or False: If the R isomer of a molecule has an optical rotation of + 25.7 degree then the S isomer of the molecule will have an optical rotation of -25.7 degree.

If we have the exact opposite (as we have in this case) the magnitud of the optical activity value will remain and the sign will change. TRUE

-)True or False: A CN is a higher priority than a CH2OH.

In this case, a carbon is directly bonded to the chiral carbon. The carbon on CN is bonded to a nitrogen atom and the carbon on CH2OH is bonded to an oxygen. So, the CH2OH will have more priority because O has a higher atomic number. FALSE

-)True or False: All molecules with chiral centers are optically active.

We can have for example mesocompounds in which the optical activity is canceled out due to symmetry planes. FALSE

-)True or False: To have an enantiomer a molecule must have at least two chiral centers.

A pair of enantiomers is made between at least 1 chiral carbon. Enantiomer R and enantiomer S. FALSE

-)True or False: Chiral molecules are always optically active.

We can have racemic mixtures or mesocompounds with chiral carbons but without optical activity. FALSE

-)True or False: A CH2CH2Br is higher priority than a CH2F.

The "Br" atom is bonded in the third carbon (respect to the chiral carbon) and the "F" atom is bonded to the second carbon. Therefore CH2F has more priority than CH2CH2Br. FALSE

-)True or False: Meso molecules with two stereocenters have a R,S configuration.

On the compounds with R and S configuration at the same time can have symmetry planes so, we will not have optical activity. TRUE

True or False: Diastereomers have the same physical properties except in a chiral environment.

All diastereomers have the same physical properties. TRUE

True or False: Compound H has an optical activity of 0.

We have to have the structure of the compound.

True or False: A C=C double bond is higher priority than a -CH(CH3)2.

In the case of C=C, we can say that is equivalent to two carbon bonds without hydrogens. Therefore C=C has higher priority. TRUE

6 0

3 years ago

What are the three states of matter?

nataly862011 [7]

SOLID

LIQUID

GASES .......

4 0

2 years ago

During a spectrophotometric analysis of an unknown, you measure your solution's absorbance, and the value is higher than the hig

Reil [10]

Answer:

A) Dilute the unknown so that it will have an absorbance within the standard curve. Once the diluted unknown concentration is determined, the full strength concentration can be calculated if the dilution process is recorded. Beer's law only applies to dilute solutions, so diluting the unknown is better than making new standards.

Explanation:

Beer's law states that absorbance is proportional to the concentrations of the absorbing species. This is verified in the case of diluted solutions (0≤0.01 M) of most substances. As a solution gets more concentrated, solute molecules interact between themselves because of their proximity. When a molecule interacts with another, the change in their electric properties (including absorbance) is probable. That's why the plot of absorbance versus concentration stops being a straight line, and Beer's law is no longer valid.

Therefore, if the absorbance value is higher than the highest standard, dilutions should be made. Once this concentration is determined, the full strength concentration can be calculated with the inverse of the dilution.

7 0

3 years ago

What does the symbol Cp

xenn [34]

Answer:

From what i've learned so far, the correct answer is "Heat at a constant Pressure" or "Specific Heat"

Explanation:

Hope this helps!

8 0

2 years ago

Check all that apply...helppppp

mote1985 [20]

Answer:

dfgh

Explanation:

3 0

2 years ago