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irakobra [83]
3 years ago
9

Water is a pure substance. Which of the following is true about water? (4 points) Its compounds can only be physically separated

into the elements that make it up. It is made up of a variety of compounds, each with a different set of properties. It is made up of one element and one compound, each with the same properties.
Chemistry
1 answer:
jonny [76]3 years ago
7 0

Answer:

Water/H20 is a compound made of hydrogen and oxygen. Although water is the most abundant substance on earth, it is rarely found naturally in its pure form. Most of the time, pure water has to be created. Pure water is called distilled water or deionized water.

Explanation:

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C, it prevents the Earth from ultraviolet radiation and other harmful substances from space
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How many grams of ethylene glycol (c2h6o2 must be added to 1.25 kg of water to produce a solution that freezes at -5.88 ∘c?
e-lub [12.9K]
The freezing point depression is calculated through the equation,
                                    ΔT = (kf)  x m 
where ΔT is the difference in temperature, kf is the freezing point depression constant (1.86°C/m), and m is the molality. Substituting the known values,
                                   5.88 = (1.86)(m)
m is equal to 3.16m

Recall that molality is calculated through the equation,
                                  molality = number of mols / kg of solvent
                                       number of mols = (3.16)(1.25) = 3.95 moles
Then, we multiply the calculated amount in moles with the molar mass of ethylene glycol and the answer would be 244.9 g.

6 0
3 years ago
The reaction 2NO(g)+O2(g)−→−2NO2(g) is second order in NO and first order in O2. When [NO]=0.040M, and [O2]=0.035M, the observed
Oksanka [162]

Answer:

(a) The rate of disappearance of O_{2} is: 4.65*10^{-5} M/s

(b) The value of rate constant is: 0.83036 M^{-2}s^{-1}

(c) The units of rate constant is:  M^{-2}s^{-1}

(d) The rate will increase by a factor of 3.24

Explanation:

The rate of a reaction can be expressed in terms of the concentrations of the reactants and products in accordance with the balanced equation.

For the given reaction:

2NO(g)+O_{2}->2NO_{2}

rate = -\frac{1}{2} \frac{d}{dt}[NO] = -\frac{d}{dt}[O_{2}] = \frac{1}{2}\frac{d}{dt}[NO_{2}] -----(1)

According to the question, the reaction is second order in NO and first order in  O_{2}.

Then we can say that, rate = k[NO]^{2}[O_{2}] -----(2)

where k is the rate constant.

The rate of disappearance of NO is given:

-\frac{d}{dt}[NO] = 9.3*10^{-5} M/s.

(a) From (1), we can get the rate of disappearance of O_{2}.

    Rate of disappearance of  O_{2} = -\frac{d}{dt}[O_{2}] = (0.5)*(9.3*10^{-5}) M/s = 4.65*10^{-5} M/s.

(b) The rate of the reaction can be obtained from (1).

    rate = -\frac{1}{2} \frac{d}{dt}[NO] = (0.5)*(9.3*10^{-5})

    rate = 4.65*10^{-5} M/s

   The value of rate constant can be obtained by using (2).

    rate constant = k = \frac{rate}{[NO]^{2}[O_{2}]}

    k = \frac{4.65*10^{-5}}{(0.040)^{2}(0.035)} = 0.83036 M^{-2}s^{-1}

(c) The units of the rate constant can be obtained from (2).

    k = \frac{rate}{[NO]^{2}[O_{2}]}

    Substituting the units of rate as M/s and concentrations as M, we get:

\frac{Ms^{-1} }{M^{3}} = M^{-2}s^{-1}

(d) The reaction is second order in NO. Rate is proportional to square of the concentration of NO.

     rate\alpha [NO]^{2}

If the concentration of NO increases by a factor of 1.8, the rate will increase by a factor of (1.8)^{2} = 3.24

     

5 0
3 years ago
Decreasing the temperature of the reaction 3H2 + N2<----->2NH3. In this reaction, the product absorbs heat. WHICH WAY WILL
AURORKA [14]

3H_{2}+N_{2}⇔2NH_{3}

Decreasing the temperature of the reaction,the reaction shifts forward.

The explanation is given below.

Explanation:

If the temperature of the reaction mixture is increased,then the equilibrium will shift to decrease the temperature.

If the temperature of the reaction mixture is decreased,then the equilibrium will shift to increase the temperature.

During the formation of the ammonia,it gives off heat.So it is an exothermic reaction.

3H_{2}+N_{2}⇔2NH_{3}

A decrease in the temperature favors the reaction that is exothermic (the forward reaction)because it produces energy.Therefore,if the temperature is decreased,the yield of the ammonia increases.

<em>Therefore if the temperature is increased,the reaction shifts forward and the yield of the ammonia increases and it is an exothermic reaction.</em>

7 0
3 years ago
"which is a correct description of the organization of subatomic particles in atoms?"
Irina18 [472]
Which is a correct description of the organization of subatomic particles in atoms?

Protons and neutrons are tightly packed into a small nucleus. Electrons occupy the space
outside the nucleus

hope this helps.
5 0
3 years ago
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