CHEMISTRY HIGH SCHOOL

The_____is an organelle that can give instructions for a
cell to reproduce and send directions to organelles to make needed
materials.

Answers

Answer 1
Answer:

Answer:

nnmnm

Explanation:

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An automobile antifreeze mixture is made by mixing equal volumes of ethylene glycol (d = 1.114 g/mL; M = 62.07 g/mol) and water (d = 1.00 g/mL) at 20°C. The density of the mixture is 1.070 g/mL. Express the concentration of ethylene glycol as (a) volume percent 50 % v/v (b) mass percent 52.7 % w/w (c) molarity M (d) molality m (e) mole fraction

Answers

Answer :

(a) The volume percent is, 50.63 %

(b) The mass percent is, 52.69 %

(c) Molarity is, 9.087 mole/L

(d) Molality is, 17.947 mole/L

(e) Moles fraction of ethylene glycol is, 0.244

Explanation : Given,

Density of ethylene glycol = 1.114 g/mL

Molar mass of ethylene glycol = 62.07 g/mole

Density of water = 1.00 g/mL

Density of solution or mixture = 1.070 g/mL

According to the question, the mixture is made by mixing equal volumes of ethylene glycol and water.

Suppose the volume of each component in the mixture is, 1 mL

First we have to calculate the mass of ethylene glycol.

\text{Mass of ethylene glycol}=\text{Density of ethylene glycol}* \text{Volume of ethylene glycol}=1.114g/mL* 1mL=1.114g

Now we have to calculate the mass of water.

\text{Mass of water}=\text{Density of water}* \text{Volume of water}=1.00g/mL* 1mL=1.00g

Now we have to calculate the mass of solution.

Mass of solution = Mass of ethylene glycol + Mass of water

Mass of solution = 1.114 + 1.00 = 2.114 g

Now we have to calculate the volume of solution.

\text{Volume of solution}=\frac{\text{Mass of solution}}{\text{Density of solution}}=(2.114g)/(1.070g/mL)=1.975mL

(a) Now we have to calculate the volume percent.

\text{Volume percent}=\frac{\text{Volume of ethylene glycol}}{\text{Volume of solution}}* 100=(1mL)/(1.975mL)* 100=50.63\%

(b) Now we have to calculate the mass percent.

\text{Mass percent}=\frac{\text{Mass of ethylene glycol}}{\text{Mass of solution}}* 100=(1.114g)/(2.114g)* 100=52.69\%

(c) Now we have to calculate the molarity.

\text{Molarity}=\frac{\text{Mass of ethylene glycol}* 1000}{\text{Molar mass of ethylene glycol}* \text{Volume of solution (in mL)}}

\text{Molarity}=(1.114g* 1000)/(62.07g/mole* 1.975L)=9.087mole/L

(d) Now we have to calculate the molality.

\text{Molality}=\frac{\text{Mass of ethylene glycol}* 1000}{\text{Molar mass of ethylene glycol}* \text{Mass of water (in g)}}

\text{Molality}=(1.114g* 1000)/(62.07g/mole* 1kg)=17.947mole/kg

(e) Now we have to calculate the mole fraction of ethylene glycol.

\text{Mole fraction of ethylene glycol}=\frac{\text{Moles of ethylene glycol}}{\text{Moles of ethylene glycol}+\text{Moles of water}}

\text{Moles of ethylene glycol}=\frac{\text{Mass of ethylene glycol}}{\text{Molar of ethylene glycol}}=(1.114g)/(62.07g/mole)=0.01795mole

\text{Moles of water}=\frac{\text{Mass of water}}{\text{Molar of water}}=(1g)/(18g/mole)=0.0555mole

\text{Mole fraction of ethylene glycol}=(0.01795mole)/(0.01795mole+0.0555mole)=0.244

The greatest amount of energy released per gram of reactants occurs during a(1) redox reaction(2) fission reaction
(3) substitution reaction
(4) neutralization reaction

Answers

Answer : The correct option is, (2) Fission reaction.

Explanation :

  • Fission reaction : This is a type of nuclear reaction in which the splitting of bigger nuclei into two smaller nuclei takes place. During this process, the large amount of energy is released.
  • Redox reaction : This is an oxidation-reduction reaction in which the electrons transferred between the two molecules.
  • Substitution reaction : In this reaction, one functional group is replaced by the another functional group in a chemical compound.
  • Neutralization reaction : In this reaction, the acid and base react to give water and a salt.

Redox reaction, substitution reaction and neutralization reaction are the chemical reactions in which the heat releases when the chemical bonds are breaking and forming.

Therefore, the greatest amount of energy released per gram of reactants occurs during the fission reaction.
The answer is (2) fission reaction. The other three are chemical reaction, so they change the chemical energy to heat to release when chemical bonds breaking and forming . But for fission reaction, the nucleus have been changed. So the mass change to energy to release.

According to Hess’s law, if a series of intermediate reactions are combined, the enthalpy change of the overall reaction isthe difference between the enthalpies of the intermediate reactions.
the sum of the enthalpy changes of the intermediate reactions.
the product of the enthalpy changes of the intermediate reactions.
the fraction of the individual enthalpies of the intermediate reactions.

Answers

Answer : The correct option is, the sum of the enthalpy changes of the intermediate reactions.

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

For example :

The formation reaction of CO will be,

C(graphite)+(1)/(2)O_2(g)\rightarrow CO(g)    \Delta H_(formation)

The intermediate balanced chemical reaction will be,

(1) C(graphite)+(1)/(2)O_2(g)\rightarrow CO_2(g)    \Delta H_1

(2)CO+(1)/(2)O_2(g)\rightarrow CO_2(g)    \Delta H_2

The expression for enthalpy of formation of CO is,

\Delta H_(formation)=[n* \Delta H_1]+[n* \Delta H_2]

where,

n = number of moles

By adding reaction 1 and reverse reaction of reaction 2, we get the enthalpy of formation of CO.

Hence, the correct option is, the sum of the enthalpy changes of the intermediate reactions.
I think the answer is B. the sum of the enthalpy changes of the intermidiate reactions

Which class of elements best conducts electricity

Answers

Metals best conducts electicity
metals conduct all electricity.

Which statement correctly describes the charge of the nucleus and the charge of the electron cloud of an atom?(1) The nucleus is positive and the electron cloud is positive.
(2) The nucleus is positive and the electron cloud is negative.
(3) The nucleus is negative and the electron cloud is positive.
(4) The nucleus is negative and the electron cloud is negative.

Answers

Atoms are made of nucleus and electrons. Nucleus have a positive charge due to the presence of protons and electrons are negative in charge . Thus option 2 is correct.

What is an atom?

Atoms are the basic unit every substance. Atoms combines to form molecules and compounds. An atom is made of nucleus and surrounding electrons which are revolving through a circular path of fixed energy.

Nucleus is the core of the atom and the 90% of the weight of atom is centered in the nucleus and it contains positively charged protons and neutral particles neutrons.

The nuclear model of atom was first proposed by Rutherford. He found the positive cloud of the atom and and named as nucleus. He discovered the positively charged particles protons.

The net charge of an atom is zero because all the positive charges are neutralised by equal number of negatively charged particles electrons.

Therefore, the nucleus is positive and the electron cloud is negative and option 2 is correct.

To find more about atomic nucleus, refer the link below:

brainly.com/question/10658589

#SPJ2
The nucleus of an atom is positive, because it contains the protons (+1 charge) and neutrons (0 charge)
The electron cloud has a negative charge, because electrons have a -1 charge
So the answer is (2)

Which best describes the effect of J. J. Thomson’s discovery?

Answers

The correct answer for the question that is being presented above is this one: "A. The accepted model of the atom was changed." J J Thomson discovered the electrons and performed experiment using the cathode ray tube
Here are the following choices:
A. The accepted model of the atom was changed.
B. The accepted model of the atom was supported.
C. Cathode ray tubes were no longer used in experiments due to poor results.
D. Cathode ray tubes became the only instrument of use in the study of atoms
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