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3 years ago

Elaborate on the reason why heating water up will increase the rate of dissolving for a solute.

2 answers:

5 0

<span> D) <span> <span> <span> The average kinetic energy of the molecules that make up the solution also increases with increasing temperature. This increase in kinetic energy allows the solvent molecules to more effectively break apart the solute molecules that are held together by intermolecular attractions. </span></span></span></span>

nirvana33 [79]3 years ago

3 0

<h3><u>Answer;</u></h3>

D) The average kinetic energy of the molecules that make up the solution also increases with increasing temperature. This increase in kinetic energy allows the solvent molecules to more effectively break apart the solute molecules that are held together by inter-molecular attractions.

<h3>Explanation;</h3>

<em><u>Solubility refers to the amount of a substance that can dissolve in a solution at a given temperature.</u></em>
<em><u>Solubility increases with increase in temperature, this is because higher temperature of the solvents increases the kinetic energy of the particles in the solvent, thus they will vibrate more faster, which makes them to break apart the molecules of the solute that are held by inter-molecular forces more effectively.</u></em>

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1. A metal ball has a mass of 20 g and a volume of 6 cm3.Find its density

vesna_86 [32]

Answer:

density of the ball is 3.33 g/cc

Explanation:

As we know that the density is the ratio of mass and volume

here we know that

mass = 20 g

volume = 6 cubic cm

so we will have

$\rho = \frac{m}{V}$

$\rho = \frac{20}{6} g/cm^3$

$\rho = 3.33 g/cm^3$

4 0

3 years ago

Energy is conventionally measured in Calories as well as in joules. One Calorie in nutrition is one kilocalorie, defined as 1 kc

Sergeeva-Olga [200]

Answer:

a) The student must run flight of stairs to lose 1.00 kg of fat 709.5 times.

b) Average power

P(w)= 1062.07 [w]

P(hp)=1.42 [hp]

c) This activity is highly unpractical, because the high amount of repetitions he has to due in order to lose, just 1 Kg of fat.

Explanation:

First, lets consider the required amount of work to move the mass of the student. (considering running stairs just as a vertical movement)

Work:

$W= F*d= m*g*d$

Where m is the mass of the student, g is gravity (9.8 m/s) and d is the total distance going up the stairs (0.15m *85steps= 12.75m )

$W= F*d= m*g*d=85* 9.8*12.75=10620.75 [J]$

Converting from Joules to Kcals:

$\frac{10620.75}{4186} =2.537 Kcal$

Now lets take into account the efficiency of the human body (20%)

2.537 ---> 20%

x ---> 100%

$x=\frac{2.537*100}{20} =12.685$

So the student is consuming 12.685 KCals each time he runs up the stairs.

Now,

1 g --> 9 Kcals

1000 g --> 9000KCals

Burning 1 g of fat, requieres 9 KCals, 1000g burns 9000KCals. So in order to burn a 1Kg of fat:

$\frac{9000Kcals}{12.685Kcals} =709.5 times$

He must run up the stairs 709.5 times, to burn 1 Kg of fat.

********************

For b) just converting units, taking into account the time lapse. (53103.75 is the 100% of the energy in joules, from converting 12.685Kcals to joules)

$Power=\frac{Joules}{Seconds} =\frac{53103.75}{50} =1062.075 [W]\\$

$P(hp)=\frac{P(w)}{745.7} =\frac{1062.075}{745.7} =1.42[hp]$

*****

4 0

3 years ago

In odd nuclei, what determines the final spin of the nucleus?

Katen [24]

Answer:

In odd nuclei, the left out proton or neutron will contribute to the spin of the nucleus.

Explanation:

The meaning of odd nuclei is atomic mass is odd.

A=odd number.

A=Z+n

Here, Z is proton either it will odd or n will odd which is neutron.

Now according to the shell model the left out proton or neutron will contribute to the spin and parity.

For example,

Take the case of isotope of nitrogen-15.

Here Z is 7, and n is 8 will not contribute in spin.

Now, for Z=7.

$1S^{2} _{\frac{1}{2} }, 1P^{4} _{\frac{3}{2} }, 1P^{1} _{\frac{1}{2} }$

Here,

$j=\frac{1}{2}$

and, L=1.

Fort parity,

$(-1)^{L}$

Put the value of L.

Parity will be -1.

Now, spin will be

$S=(\frac{1}{2} )^{-1}$ .

7 0

3 years ago

1) The energy held in the molecules that your lunch is composed of

Rasek [7]

Answer:

Chemical energy

Explanation:

The energy held in the foods molecules a lunch pack is composed of is chemical energy.

They occur within food substances which originates from plants and animals as giant organic molecules.

Since food is often derived from plants and animals.
Plants produce their own food by producing macromolecules from simple inorganic substances in the environment.
Animals takes up these food and build their own body through it.
Plants and animal parts constitutes organic molecules in which chemical energy is duly stored.
When the molecules are broken down, they released their chemical potential energy into heat energy.

4 0

3 years ago

Spiders may "tune" strands of their webs to give an enhanced response at frequencies corresponding to the frequencies at which d

Bingel [31]

Answer:

0.0000167283525619 N

Explanation:

$\rho$ = Density of silk = 1300 kg/m³

d = Diameter = 0.002 mm

r = Radius = 0.001 mm

l = Length = 16 cm

f = Frequency = 200 Hz

Mass of the string is

$m=\rho V\\\Rightarrow m=\rho Al\\\Rightarrow m=1300\times \pi (0.001\times 10^{-3})^2\times 0.16\\\Rightarrow m=6.5345127195\times 10^{-10}\ kg$

Frequency is given by

$f=\dfrac{1}{2l}\sqrt{\dfrac{T}{m/l}}\\\Rightarrow T=4lf^2m\\\Rightarrow T=4\times 0.16\times 200^2\times 6.5345127195\times 10^{-10}\\\Rightarrow T=0.0000167283525619\ N$

The tension on the string is 0.0000167283525619 N

3 0

3 years ago