A student uses visible spectrophotometry to determine the concentration of CoCl2(aq) in a sample solution. First the student prepares a set of CoCl2(aq) solutions of known concentration. Then the student uses a spectrophotometer to determine the absorbance of each of the standard solutions at a wavelength of 510nm and constructs a standard curve. Finally, the student determines the absorbance of the sample of unknown concentration.

The original solution used to make the solutions for the standard curve was prepared by dissolving 2.60g of CoCl2 (molar mass 130.g/mol) in enough water to make 100.mL of solution. What is the molar concentration of the solution?

A) 0.200 mol
B) 0.500 mol
C) 1.00 mol
D) 5.00 mol

Answer:

At the Earth's surface, wind blows horizontally from high pressure to low pressure areas. The speed is determined by the rate of air pressure change, or gradient, between the two pressure areas. The greater the pressure difference, the faster the winds.

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The Four Forces That Influence Wind Speed & Wind Direction

Explanation:

The chemical formula for an ionic compound represents the simplest ratio of ions that results in an electrically neutral compound. That is option D.

An ionic chemical compound is defined as the type of chemical compound that contains both the oppositely-charged ions of a metal and a nonmetal are attracted reacting with each other to form an ionic bond.

When represented as a chemical formula, it is the simplest ratio of ions that results in an electrically neutral compound.

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I think it's D

Hope that helps

Answer: B, the bonding in the compound is nonpolar covalent.

Explanation:

This is because with the same electronegativity, there is an equal sharing of electrons, which indicates that the bonding must be nonpolar.

Answer:

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

mass = Density × volume

From the question we have

mass = 0.917 × 2.5 = 2.2925

We have the final answer as

Hope this helps you

Answer:. 2.3 g

Explanation:

Answer:

The answer is that light is faster than sound.

Explanation:

A good example is of lightning and thunder during a thunderstorm.

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Answer:

a and d

Explanation:

Answer:

Viscosity

Explanation:

The viscosity of the liquid is the independent variable. The flow rate is the dependent variable in this hypothesis.

The statement given is called the hypothesis. It is a form of scientific guess into a phenomenon.

Answer:

67.6 years is the time the isotope take to decay from 0.900g to 0.170g

Explanation:

The radioactive decay follows first order law:

Ln [A] = -kt + ln[A]₀

Where [A] is concentration after time t,

k is decay constant:

k = ln 2 / t(1/2)

k = ln2 / 28.1 years

k = 0.02467 years⁻¹

[A]₀ = Initial concentration.

We can replace concentration and use the mass of the isotope:

Ln [A] = -kt + ln[A]₀

Ln [0.170g] = -0.02467 years⁻¹t + ln[0.900g]

-1.667 = -0.02467 years⁻¹t

t =

The time required for the sample to reduce to 0.170 grams has been 67.75 years.

Half-life can be defined as the times required by the substance to reduce to half of its initial concentration.

The half-life can be expressed as:

Amount left = Initial amount [tex]\times[/tex] [tex]\rm \dfrac{1}{2}^\dfrac{time}{Half-life}[/tex]

From the given:

0.17 g = 0.9 [tex]\rm \times\;\dfrac{1}{2}^\dfrac{t}{28.1}[/tex]

[tex]\rm \dfrac{0.17}{0.9}[/tex] = [tex]\rm \dfrac{1}{2}^\dfrac{t}{28.1}[/tex]

0.188 = [tex]\rm (0.5)^\dfrac{t}{28.1}[/tex]

Taking log on both the sides,

log 0.188 = [tex]\rm \dfrac{t}{28.1}\;\times[/tex] log 0.5

2.411 = [tex]\rm\dfrac{t}{28.1}[/tex]

t = 2.411 [tex]\times[/tex] 28.1 years

Time = 67.75 years.

The time required for the sample to reduce to 0.170 grams has been 67.75 years.

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The balanced coefficients in the reaction are now; 2, 3, 1, 3.

A balanced chemical reaction equation is one in which the number of atoms of each element on the right hand side of the reaction equation is equal to the number of atoms of the same element on the left hand side of the reaction equation.

For the reaction show, the balanced reaction equation is; 2Al(NO3)3 + 3Na2S → Al2S3 +3 Na(NO3). The balanced coefficients in the reaction are now; 2, 3, 1, 3.

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Answer:

[tex]\frac{1 mole of N_{2} }{3 moles of H_{2} }[/tex]

Explanation:

The equation of the reaction:

   Nitrogen gas N₂ reacts with Hydrogen as H₂ to produce ammonia NH₃;

          N₂    +    H₂    →    NH₃  

 The balanced equation is ;

        N₂    +    3H₂    →    2NH₃  

The mole ratio is the ratio of the coefficients of the combining reactants;

   1 mole of N₂ combines with 3 mole of H₂;

So;

      [tex]\frac{1 mole of N_{2} }{3 moles of H_{2} }[/tex]

Answer:

B

Explanation:

Answer:

B. Always add the acid to the water slowly, taking a moment to stir between drops

Answer: the molar mass will be too high

Explanation:

Answer:

Iron slowly reacts with oxygen and forms rust. In this case, the reactants are iron and oxygen. The product is rust, or iron oxide. The chemical equation looks like this:

Explanation:

iron + oxygen → iron oxide

Answer:

Iron slowly reacts with oxygen and forms rust. In this case, the reactants are iron and oxygen. The product is rust, or iron oxide. The chemical equation looks like this:

iron + oxygen → iron oxide

Explanation:

This was the answer straight from Plato. I hope that this helped you, please mark me the brainiest, like and rate my answer if it did! :)

Cyclops are heterotrophic

The value of x = 3

Fusion and fission reactions are reactions involving atomic nucleus reactions

Fission reaction is a nucleation division reaction by firing a particle usually neutron so that it gets smaller particles of atomic nuclei.

Fission of Uranium-235

[tex]\tt ^1_0n+^{235}_{92}U\rightarrow ^{141}_{56}Ba+^{92}_{36}Kr+3^1_0n[/tex]

In this reaction, the sum of the mass number and atomic number of the elements involved in the reaction will be equal

atomic number left : 0+92=92

atomic number right : 56+36=92

mass number left : 1+235=236

mass number right : 141+92+3=236

The value of x in the fission process of uranium has been 3.

Fission reaction has been the nuclear reaction resulting in the breaking of the element into smaller substituents. The fission of uranium has been:

n +  U [tex]\rightarrow[/tex] Ba + Kr + n

In the given fission reaction, the mass number of the atoms on the right and left of the reaction has to be equal. The mass number has been;

235 + 1 = 141 + 92 + x

236 = 233 + x

x = 236 -233

x = 3

The value of x in the fission process of uranium has been 3.

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Answer:

answer is D

Explanation:

Answer:

Lithium

Explanation:

The element with electronic configuration of 2, 1 is helium.

In the electronic configuration, we are able to know that the total number of electrons the atom contains is 3. Also, the element has one electron in the outer most shell.

Elements with one valence electrons are the alkali metals.

Therefore, this configuration clearly matches Lithium.

Answer:

hail, btw have a nice day

Answer:

Hail

Explanation:

I got it right on my test

Answer:

125 cubic meters

Explanation:

Subtract 375-250=125 cubic meters

Answer:

5 moles of oxygen occupy 120 dm³ volume.

Explanation:

Given data:

Number of moles = 5 mol

Volume of gas = ?

Solution:

In question it is given gas is at room temperature and pressure.

One mole of any gas at room room temperature and pressure occupy volume of 24 dm³. Thus,

5 mole of gas occupy volume of,

5 mol × 24 dm³/1 mol

120 dm³

5 moles of oxygen occupy 120 dm³ volume.

Answer:

Acid rain

Explanation:

The independent variable in the hypothesis statement is the acid rain. An independent variable is usually the cause in an experiment.

This variable give rises to the effects observed as the dependent variable.

In the presence of the acid rain, the fish population will increase.

The dependent variable is the fish population or number of fishes.

The independent variable is the acid rain as it is the cause of the effect observed on the fish population.

Answer:

Newton's First Law...

Explanation:

The only force that acts on the car is the sudden deceleration from v to 0 velocity in a brief period of time, due to the collision with another object. However, when viewing the total system, the collision in the situation with two cars releases twice as much energy as the collision with a wall

Answer:

Explanation:

we dream because when our bodies are taking memories into long term, the memories from that day or the day before collide and make dreams. that is why they resemble things that have happened to us.

Answer:

One widely held theory about the purpose of dreams is that they help you store important memories and things you've learned, get rid of unimportant memories, and sort through complicated thoughts and feelings. Research shows that sleep helps store memories.

The brain is so active when we dream that it is virtually indistinguishable from a brain in the waking state. Even so, the chemistry of it is entirely rewired when we sleep. Many scientists attribute this to the reason dreams are so strange and bizarre.

Explanation: