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3 years ago

The atomic radius of main group elements generally increases down a group because

1 answer:

8 0

The atomic radius of main group elements generally increases down a group because as there are more electrons they are farther away from the nucleus and the electrons closer to the nucleus shield the outer electrons from the protons for attraction.

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What are two reasons that someone would want to become a scientist?<br> 1 point<br> Your answer

kari74 [83]

Two reason someone would want to become a scientist to make exciting discoveries and discovered new life on our planet. Also you could solve huge problems that somebody else couldn’t solved. This is why somebody would want to be a scientist.

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3 years ago

lilavasa [31]

1.66 M is the concentration of the chemist's working solution.

<h3>What is molarity?</h3>

Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution. Molarity is also known as the molar concentration of a solution.

In this case, we have a solution of Zn(NO₃)₂.

The chemist wants to prepare a dilute solution of this reactant.

The stock solution of the nitrate has a concentration of 4.93 M, and he wants to prepare 620 mL of a more dilute concentration of the same solution. He adds 210 mL of the stock and completes it with water until it reaches 620 mL.

We want to know the concentration of this diluted solution.

As we are working with the same solution, we can assume that the moles of the stock solution will be conserved in the diluted solution so:

$n_1$ = $n_2$ (1)

and we also know that:

n = M x $V_2$

If we replace this expression in (1) we have:

$M_1$ x $V_1$ = $M_2$ x $V_2$

Where 1, would be the stock solution and 2, the solution we want to prepare.

So, we already know the concentration and volume used of the stock solution and the desired volume of the diluted one, therefore, all we have to do is replace the given data in (2) and solve for the concentration which is $M_2$ :

4.93 x 210 = 620 x $M_2$

$M_2$ = 1.66 M

This is the concentration of the solution prepared.

Learn more about molarity here:

brainly.com/question/19517011

#SPJ1

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2 years ago

What are accounts for physical properties?

Nezavi [6.7K]

Freezing point, boiling point, melting point, smell, attraction or repulsion to magnets, colour change, and many more examples.

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3 years ago

A first order reaction has rate constants of 4.6 x 10-2 s-1 and 8.1 x 10-2 s-1 at 0ºC and 20ºC, respectively. What is the value

Airida [17]

Answer:

D. 18,800 J/mol

Explanation:

We need to use the Arrhenius equation to solve for this problem:

$k=Ae^{\frac{-E_a}{RT}$ , where k is the rate constant, A is the frequency factor, $E_a$ is the activation energy, R is the gas constant, and T is the temperature in Kelvins.

We want to find the value of $E_a$ , so let's plug some of the information we have into the equation. The gas constant we can use here is 8.31 J/mol-K.

At 0°C, which is 0 + 273 = 273 Kelvins, the rate constant k is $4.6*10^{-2}$ . So:

$k=Ae^{\frac{-E_a}{RT}$

$4.6*10^{-2}=Ae^{\frac{-E_a}{8.31*273}$

At 20°C, which is 20 + 273 = 293 Kelvins, the rate constant k is $8.1*10^{-2}$ . So:

$k=Ae^{\frac{-E_a}{RT}$

$8.1*10^{-2}=Ae^{\frac{-E_a}{8.31*293}$

We now have two equations and two variables to solve for. We just want to find Ea, so let's write the first equation for A in terms of Ea:

$4.6*10^{-2}=Ae^{\frac{-E_a}{8.31*273}$

$A=\frac{4.6*10^{-2}}{e^{\frac{-E_a}{8.31*273}} }$

Plug this in for A in the second equation:

$8.1*10^{-2}=Ae^{\frac{-E_a}{8.31*293}$

$8.1*10^{-2}=\frac{4.6*10^{-2}}{e^{\frac{-E_a}{8.31*273}} }e^{\frac{-E_a}{8.31*293}$

After some troublesome manipulation, the answer should come down to be approximately:

Ea = 18,800 J/mol

The answer is thus D.

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3 years ago

What volume in milliliters of 0.0130 M Ca(OH)₂ is required to neutralize 75.0 mL of 0.0300 M HCl?

Orlov [11]

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3 years ago