A student performs an experiment in which 5.0 g of potassium chloride, KCI, are dissolved into 100.0 mL of distilled water. The student records the
temperature both before and after dissolving the KCl into the water, as shown in the data table below. Use this data to answer the question that follows.
Initial Temperature, °C Final Temperature, °C
21.8°C
16.4°C
Which statement below is a correct conclusion based on these results ?
The temperature of the water decreases and so the reaction is exothermic
The temperature of the water increases and so the reaction is exothermic
The temperature of the water decreases and so the reaction is endothermic
The temperature of the water increases and so the reaction is endothermic

Answer:

Iron is natural. Paper is man-made

Explanation:

Answer:

iron

Explanation:

Answer:

ok  

Explanation:

Answer:

cells are a basic unit of structure and function all things

High concentrations of carbon dioxide make it harder for marine animals to respire (to extract oxygen from seawater). This, in turn, makes it harder for these animals to find food, avoid predators, and reproduce. Low concentrations of oxygen can have similar effect

Becay the Ocean's Carbon Balance. The idea seemed simple enough: the more carbon dioxide that people pumped into the atmosphere by burning fossil fuels, the more the oceans would absorb. ... Water trapped at the surface would become saturated, at which point, the ocean would slow its carbon uptake.

Answer:

E = 165.75×10⁻²⁶ J

Explanation:

Given data:

Wavelength = 0.12 m

Energy of wave = ?

Solution:

Formula:

E = h c/λ

c = 3×10⁸ m/s

h = 6.63×10⁻³⁴ Js

Now we will put the values in formula.

E = 6.63×10⁻³⁴ Js × 3×10⁸ m/s / 0.12 m

E = 19.89×10⁻²⁶ J.m / 0.12 m

E = 165.75×10⁻²⁶ J

For the extraction of at least 95% of Y in water, 3 extractions are to be performed.

Distribution coefficient can be defined as the ratio of the concentration of solute in an organic solvent to water.

Distribution coefficient = [tex]\rm \dfrac{concentration\;in\;solvent}{concentration\;in\;water}[/tex]

Concentration in water = 100-X per 50 ml

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{100-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{100-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{1000-X}[/tex]

4000 - 4X = 50X

X = 74.1 %

Thus, after the first extraction, the amount of Y extracted is 74.1%.

We have to extract at least 95% of Y. Thus, the second extraction is performed.

Remaining y = 25.9%

The concentration in organic solvent = X per 10 ml

Concentration in water = 25.9 -X

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{25.9-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{25.9-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{259-X}[/tex]

1036 - 4X = 50X

X = 19.2%

Thus, after the second extraction the amount of Y extarcted = first extraction + second extraction

The amount of Y extracted = 74.1 + 19.2 %

The amount of Y extracted = 93.3%

The remaining Y for third extraction = 100 - 93.3

The remaining Y for the third extraction = 6.7%

Concentration in water = 100 - 6.7

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{6.7-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{6.7-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{67-X}[/tex]

268 - 4X = 50X

X = 5.0%

The total extraction after third extraction = 93.3 + 5%

The total extraction after third extraction = 98.3%.

Thus for the extraction of at least 95% of Y in water, 3 extractions are to be performed.

For more information about the distribution coefficient, refer to the link:

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Answer:

Measure at the top of the meniscus

Hold the container (it is unsteady)

Explanation:

I'm really, really, sorry. I took chemistry in 6th grade and I'm in 8th, and I don't remember the entire list. This is all I could think of.

Answer:

In a heterogeneous mixture, the parts of the mixture are noticeably different from one another. In a homogeneous mixture, the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another.

Answer:

20000

Explanation:

Answer:

[Ar]3d4 is the ground-state electron configuration for the Mn4 ion

but i don't know whether it is paramagnetic or daimagnetic

Answer: The force on the firefly

The unfortunate firefly hitting the bus does not change the velocity of the bus very much. Technically there is a change, but it's so very small and miniscule that it barely registers. To any casual observer not paying very close attention, they don't notice anything at all. So effectively the force on the firefly is a lot greater since the firefly got the worst end of the deal.

So in short, we look at the velocity of each object and see which velocity changed the most. In this case, the firefly's velocity changed from whatever speed it was flying to 0 when it stops flying all together. That's why the force is greater on the bug.

Answer:

b.  growth in the size of the mineral grains

Explanation:

Non-foliated texture shown by a metamorphic change is depicted by growth in the size of the mineral grains.

Answer:

its b home slice

Explanation:

Answer:

A river and its tributaries make up a watershed (aka river system or drainage basin)

Pls mark me as brainliest

Answer:

river system

Explanation:

a river and all its tributaries make up a river system

Explanation:

Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic.

Answer:

Throughout the overview section following portion, the description and according to particular circumstance is defined.

Explanation:

As per the question,

⇒ [tex]NH_3(aq)+H_2O\leftrightarrow NH_4+(aq)+OH-(aq)[/tex]

⇒ [tex]NH_3+(aq) \leftrightarrow NH_3(aq)+H+(aq)[/tex]

However, it is also available in NH3 form throughout the aqueous solution much of the moment.

Answer:

if it ain't changing direction the acceleration isn't being affected

Answer:

Butanoic acid.

Explanation:

Answer:

303.6 mg

Explanation:

Given that:

The lethal dose [tex]LD_{50}[/tex] = 1320 mg/kg

The weight of the rat = 230 g

The lethal dose is the dose of a substance likely to cause death. SO a lethal dose of 50 will cause the death of 50% of the sample of test animals.

Therefore;

The mass of 2-naphthol that would have been ingested by each rat in a sample set of rats in order to kill half the population of rats will be equal to:

[tex]=\dfrac{LD_{50}}{1000} \times wt \ of \ rat[/tex]

[tex]=\dfrac{1320}{1000}\times 230[/tex]

= 303.6 mg

Answer:

The answer is: true

Explanation:

In redox reactions, the half-reactions of oxidation and reduction always occur simultaneously in pair.

The oxidation half-reaction involved the lost of electrons from a reduced substance (A) to form a oxidized substance (A⁺):

A ⇒ A⁺ + e-

In contrapossition, during the reduction half-reaction the oxidized substance (B⁺) gains electrons to form the reduced subtance (B):

B⁺ + e- ⇒ B

The overall redox reaction is obtained by the addition of the two half-reactions:

A ⇒ A⁺ + e-

B⁺ + e- ⇒ B

-----------------

A + B⁺⇒ A⁺ + B

The electrons gained by B are provided by A, which lost the same number of electrons. Thus, the oxidation/reduction reactions are paired.

Answer:

See explanation

Explanation:

At the same temperature, the average kinetic energy of gases depends on the molecular mass of the gas. Hence,  given a particular temperature, lighter molecules travel faster on the average than heavier molecules.

Considering ethanol and octane, The molar mass of ethanol is 46.07 g/mol while the molar mass of octane is 114.23 g/mol. Hence, ethanol has a greater average kinetic energy than octane at the same temperature.

Answer:

fluorine atom

Explanation:

Answer:

The radius of O^2- is  1.5*10^-8 cm and the radius of

Mg ^2+ is 6.2*10^-9 cm

Explanation:

Face centered cubic : 1/8 atoms on each edges + 1/2 atoms on each face

                                           = [tex]\frac{1}{8}* 8 + \frac{1}{2}*6[/tex]  = 4 effective atoms

MgO have a structure like NaCl forms a lattice of FCC.

density of the lattice =  [tex]\frac{ z.M}{a^3*Na}[/tex]

z : no of atoms

M: mass of the atoms

a: radius of the atom

Na: Avogadro's number

a^3(radius)  = [tex]\frac{ 4*40.3}{3.58*6.022*10^23}[/tex]

a^3 = 7.477 * 10^-23 cm^3

a = 4.21 * 10^-8 cm

Now calculating the anionic(ra O^2-) and cationic (rc Mg^2+)

in Fcc a = 2[tex]\sqrt{2} ra[/tex]

ra = 1.5*10^-8 cm

a = 2ra + 2rc

rc = a/2 -ra

rc = 6.2*10^-9 cm

The radius of O^2- is  1.5*10^-8 cm and the radius of Mg ^2+ is 6.2*10^-9 cm

The color change exhibited by phenolphthalein during a titration of aqueous acetic acid with aqueous sodium hydroxide is pink to colorless.

An indicator is an organic dye which changes color in acidic, basic and neutral medium.

Phenolphthalein is an example of an indicator. When aqueous acetic acid is titrated against aqueous sodium hydroxide, the indicator may be added to the basic solution.

Phenolphthalein has a pink color in a basic medium. As the acid is added gradually, the solution turns colorless at end point.

Hence, the color change exhibited by phenolphthalein during a titration of aqueous acetic acid with aqueous sodium hydroxide is pink to colorless.

Learn more: https://brainly.com/question/2728613

Answer:

The types of cells at work in the human body

Explanation:

Rudolf Virchow was a German physician who is known as the father of modern pathology. He contributed to the development of the cell theory by concluding that all cells come from preexisting cells. This led to the conclusion that diseases occur at the cellular level, which allowed scientists to diagnose diseases more accurately.

Considering that Virchow analyzed human cells, the image that Tumu would be most likely to use in his assignment is the one of the types of cells at work in the human body.

Answer:

D the way root cells reproduce to increase root length

Explanation:

Have a good day!

Answer:

it should be a base

Explanation:

this is because solutions such as bleach are usually slippery on the hands, and mostly bases are in cleaning solutions