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3 years ago

A sample of carbon-12 has a mass of 6.00 g. How many atoms of carbon-12 are in the sample?

Chemistry

2 answers:

nika2105 [10]3 years ago

5 0

Answer:

Explanation:

Bingel [31]3 years ago

4 0

Carbon molar mass=12
carbon mass in the above question =6
mole=number of atoms/6.02x10²³
6/12= number of atoms/6.02x10²³
number of atoms=1/2 x6.02x10²³
number of atoms= 6.02 x10²³/2
number of atoms=3.01x10²³

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The speed of light in a vacuum is 2.998 x 108 m/s. How long does it take for light to circumnavigate the Earth, which has a circ

Luba_88 [7]

Answer:

0.13 s

Explanation:

We'll begin by converting 24900 mile to metres (m). This can be obtained as follow:

1 mile = 1609.344 m

Therefore,

24900 mile = 24900 mile × 1609.344 m / 1 mile

24900 mile = 4.01×10⁷ m

Finally, we shall determine the time taken for light to circumnavigate the Earth, this can be obtained as follow:

Distance = 4.01×10⁷ m

Speed = 2.998×10⁸ m/s

Time =?

Speed = distance / time

2.998×10⁸ = 4.01×10⁷ / time

Cross multiply

2.998×10⁸ × time = 4.01×10⁷

Divide both side by 2.998×10⁸

Time = 4.01×10⁷ / 2.998×10⁸

Time = 0.13 s

Thus, it will take 0.13 s for light to circumnavigate the Earth.

5 0

3 years ago

Calculate the molarity of 0.50 mol MgCl2 in 750 ml of solution.

Vedmedyk [2.9K]

Answer : The correct answer for molarity of MgCl₂ solution is 0.67 M.

Molarity :

It expresses concentration of any solution . It can be defined as mole of solute present in volume of solution in Liter .

It uses unit M or $\frac{mol}{L}$

It can be formulated as :

$Molarity (\frac{mol}{L} ) = \frac{mole of solute (mol)}{volume of solution (L)}$

Given : mol of MgCl₂ (solute ) = 0.50 mol

Volume of solution = 750 mL

Following steps can be done :

Step 1 ) To convert volume of solution from mL to L

1 L = 1000 mL

$Volume of solution = 750 mL * \frac{1 L}{1000mL}$

Volume of solution = 0.750 L

Step 2) To find molarity

Plugging mole of solute and volume of solution in molarity formula as :

$Molarity = \frac{0.50 mol}{0.750 L }$

$Molarity = 0.67 \frac{mol}{L}$

Hence molarity of MgCl₂ solution is 0.67 M

4 0

4 years ago

Read 2 more answers

Difference between electrovalent and covalent bonding

Pie

Answer:

A covalent bond is a result of sharing electrons between two atoms. The main difference between electrovalent and covalent bond is that electrovalent bond is formed when two atoms are in an electrostatic attraction whereas covalent bond is formed when two atoms share their electrons with each other.

6 0

4 years ago

Solid lead acetate is slowly added to 75.0 mL of a 0.0492 M sodium sulfate solution. What is the concentration of lead ion requi

Firdavs [7]

Answer:

The concentration of lead ion required to just initiate precipitation is - $2.37\times10^-^5 M$

Explanation:

Lets calculate -:

Solubility equilibrium -: $PbI_2(s)$ ⇄ $Pb^2^+ (aq) + 2I^- (aq)$

Solubility product of $PbI_2$ , $Q=[Pb^2^+]_i_n_i_t_i_a_l$ $[I^-]^2_i_n_i_t_i_a_l$ $=9.8\times10^-^9$

Concentration of $I^-$ $=[KI]=0.0492M$

When the ionic product exceeds the solubility product , precipitation of salt takes place .

$Q_s_p\geq K_s_p$

$[Pb^2^+]_i_n_i_t_i_a_l$ $[I^-]^2_i_n_i_t_i_a_l$ $\geq 9.8\times10^-^9$

$[Pb^2^+]_i_n_i_t_i_a_l$ $[0.0492]^2$ $\geq 9.8\times10^-^9$

$[Pb^2^+]_i_n_i_t_i_a_l$ $\geq \frac{9.8\times10^-^9}{[0.0492]^2}$

$[Pb^2^+]_i_n_i_t_i_a_l$ $\geq$ $\frac{9.8\times10^-^9}{2.42\times10^-^3}$

$[Pb^2^+]_i_n_i_t_i_a_l$ $\geq$ $2.37\times10^-^5 M$

Thus , $PbI_2$ will start precipitating when $[Pb^2^+]_i_n_i_t_i_a_l$ $\geq 2.37\times10^-^5 M$ .

3 0

3 years ago

One possible mechanism for the gas phase reaction of hydrogen with nitrogen monoxide is: step 1 slow: H2(g) + 2 NO(g) N2O(g) + H

ddd [48]

Answer:

1) Overall reaction is

2H₂(g) + 2NO(g) → N₂(g) + 2H₂O(g)

2) The catalyst cannot be determined from the given information about this reaction. None of the species in the elementary reactions can pass as a catalyst for the reaction.

3) The only intermediate for this reaction is N₂O(g).

4) Rate = K [H₂] [NO]²

Comparing this with

Rate = K [A]ᵐ [B]ⁿ

A = H₂

B = NO

m = 1

n = 2

Explanation:

1) The overall reaction is obtained by adding all of the elementary reactions up.

Step 1 (slow step)

H₂(g) + 2 NO(g) → N₂O(g) + H₂O(g)

Step 2 (fast step)

N₂O(g) + H₂(g) → N₂(g) + H₂O(g)

Summing up, we obtain,

H₂(g) + 2 NO(g) + N₂O(g) + H₂(g) → N₂O(g) + H₂O(g) + N₂(g) + H₂O(g)

We then eliminate the species that appear on both sides of this

2H₂(g) + 2NO(g) → N₂(g) + 2H₂O(g)

2) The catalyst cannot be determined from the given information about this reaction.

The catalyst doesn't participate in the reaction, it just affects the rate of the reaction. So, none of the species in the elementary reactions can pass as a catalyst for the reaction.

3) The reaction intermediates are the species that appear in the elementary reactions but do not appear in the overall reaction. They are formed and disappear all in the process of the reaction.

From combining the elementary reactions in (1), it is evident that the only intermediate for this reaction is N₂O(g).

4) The rate law is the one that gives the rate of the overall reaction. It is obtained from the slow step of the elementary reactions. And the intermediates that appear in it are substituted using the other steps in the elementary reactions.

For this reaction, the slow step is

H₂(g) + 2 NO(g) → N₂O(g) + H₂O(g)

Rate = K [H₂] [NO]²

Since no intermediates appear in the rate law given by the slow step, there is no need for any substitution.

The rate of the overall reaction is

Rate = K [H₂] [NO]²

Comparing this with

Rate = K [A]ᵐ [B]ⁿ

A = H₂

B = NO

m = 1

n = 2

Hope this Helps!!!

6 0

3 years ago