What solid element is black, is an electrical conductor, is brittle and is found in group 4 of the periodic table?

What is the molality of a solution that is obtained by dissolving 2.922 g of NaCl into 1000.0 g of water if the molar mass of Na

never [62]

In order to find molarity, you must first find the number of moles that was dissolved.

Now, Moles = Mass ÷ Molar Mass

⇒ Moles of NaCl = 2.922 g ÷ 58.44 g/mol

= 0.05 moles

∴ the Molarity of the NaCl is 0.05 M [Option 1]

4 0

3 years ago

Which of the following observations would indicate that a material is a pure substance

Lena [83]

What is the following

3 0

3 years ago

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Which of the following is included in the measure of U.S. GDP?

finlep [7]

the value of increase in business inventories.

7 0

3 years ago

What makes physical change a physical change and a chemical change a chemical change

Snowcat [4.5K]

A physical change is any change in a substances form that does not change its chemical makeup. Examples of physical changes are breaking a stick or melting ice. A chemical change occurs when atoms of a substance are rearranged, and the bonds between the atoms are broken or formed. HOPE THIS HELPS!!

6 0

2 years ago

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2) A common "rule of thumb" -- for many reactions around room temperature is that the

babunello [35]

The question is incomplete. The complete question is :

A common "rule of thumb" for many reactions around room temperature is that the rate will double for each ten degree increase in temperature. Does the reaction you have studied seem to obey this rule? (Hint: Use your activation energy to calculate the ratio of rate constants at 300 and 310 Kelvin.)

Solutions :

If we consider the activation energy to be constant for the increase in 10 K temperature. (i.e. 300 K → 310 K), then the rate of the reaction will increase. This happens because of the change in the rate constant that leads to the change in overall rate of reaction.

Let's take :

$T_1=300 \ K$

$T_2=310 \ K$

The rate constant = $K_1 \text{ and } K_2$ respectively.

The activation energy and the Arhenius factor is same.

So by the arhenius equation,

$K_1 = Ae^{-\frac{E_a}{RT_1}}$ and $K_2 = Ae^{-\frac{E_a}{RT_2}}$

$\Rightarrow \frac{K_1}{K_2}= \frac{e^{-\frac{E_a}{RT_1}}}{e^{-\frac{E_a}{RT_2}}}$

$\Rightarrow \frac{K_1}{K_2}= e^{-\frac{E_a}{R}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)}$

$\Rightarrow \ln \frac{K_1}{K_2}= - \frac{E_a}{R} \left(\frac{1}{T_1} -\frac{1}{T_2} \right)$

$\Rightarrow \ln \frac{K_2}{K_1}= \frac{E_a}{R} \left(\frac{1}{T_1} -\frac{1}{T_2} \right)$

Given, $E_a = 0.269$ J/mol

R = 8.314 J/mol/K

$\Rightarrow \ln \frac{K_2}{K_1}= \frac{0.269}{8.314} \left(\frac{1}{300} -\frac{1}{310} \right)$

$\Rightarrow \ln \frac{K_2}{K_1}= \frac{0.269}{8.314} \times \frac{10}{300 \times 310}$

$\Rightarrow \ln \frac{K_2}{K_1}= 3.479 \times 10^{-6}$

$\Rightarrow \frac{K_2}{K_1}= e^{3.479 \times 10^{-6}}$

$\Rightarrow \frac{K_2}{K_1}= 1$

∴ $K_2=K_1$

So, no this reaction does not seem to follow the thumb rule as its activation energy is very low.

8 0

2 years ago

What solid element is black, is an electrical conductor, is brittle and is found in group 4 of the periodic table?​

What solid element is black, is an electrical conductor, is brittle and is found in group 4 of the periodic table?