Explain how a water strider can float on the surface of water without sinking.

What comes last in the scientific method

azamat

Hypothesis

Therefore the last step in the scientific method is proposing a hypothesis or obtaining a conclusion

6 0

4 years ago

In the first step of the Ostwald process for the synthesis of nitric acid, ammonia is converted to nitric oxide by the high-temp

Paul [167]

Solution: The given balanced equation is:

$4NH_3+5O_2\rightarrow 4NO+6H_2O$

If we have a hypothetical equation:

$A+2B\rightarrow 3C+5D$

Then the rate could be written as:

$rate=-\frac{\Delta [A]}{\Delta t}=-\frac{1}{2}\frac{\Delta [B]}{\Delta t}=\frac{1}{3}\frac{\Delta [C]}{\Delta t}=\frac{1}{5}\frac{\Delta [D]}{\Delta t}$

From above expression one thing could easily be noticed that the coefficients of all are inverted. Also, there is negative sign in front of reactants and positive sign in front of the products. Negative sign stands for rate of consumption where as positive sign stands for rate of formation.

Like the above example, we can write the rate for the given equation and it would be looking as:

$rate=-\frac{1}{4}\frac{\Delta [NH_3]}{\Delta t}=-\frac{1}{5}\frac{\Delta [O_2]}{\Delta t}=\frac{1}{4}\frac{\Delta [NO]}{\Delta t}=\frac{1}{6}\frac{\Delta [H_2O]}{\Delta t}$

Now we can easily answer all the parts of the question.

(a) From above expression, the rate of consumption of $O_2$ related to rate of consumption of $NH_3$ as:

$-\frac{1}{5}\frac{\Delta [O_2]}{\Delta t}=-\frac{1}{4}\frac{\Delta [NH_3]}{\Delta t}$

multiply both sides by -5

$\frac{\Delta [O_2]}{\Delta t}=\frac{5}{4}\frac{\Delta [NH_3]}{\Delta t}$

So, rate of consumption of oxygen is $\frac{5}{4}$ the rate of consumption of ammonia.

(b) The relationship between rate of formation of NO to the rate of consumption of ammonia will be written as:

$\frac{1}{4}\frac{\Delta [NO]}{\Delta t}=-\frac{1}{4}\frac{\Delta [NH_3]}{\Delta t}$

Multiply both sides by 4

$\frac{\Delta [NO]}{\Delta t}=-\frac{\Delta [NH_3]}{\Delta t}$

So, rate of formation of NO equals to the rate of consumption of ammonia.

Now, the rate of formation of $H_2O$ to the rate of consumption of ammonia would be:

$\frac{1}{6}\frac{\Delta [H_2O]}{\Delta t}=-\frac{1}{4}\frac{\Delta [NH_3]}{\Delta t}$

Multiply both sides by 6

$\frac{\Delta [H_2O]}{\Delta t}=-\frac{6}{4}\frac{\Delta [NH_3]}{\Delta t}$

So, the rate of formation of $H_2O$ is $\frac{6}{4}$ times that is 1.5 times to the rate of consumption of ammonia.

5 0

4 years ago

What is the conjugate acid of each of the following? What is the conjugate base of each?

Lilit [14]

Answer:

a. H₂O (conjugate acid) ; b. OH⁻ (conjugate base), H₃O⁺ (conjugate acid) ; c. H₂CO₃ (conjugate acid), CO₃⁻² (conjugate base) ; d. NH₄⁺ (conjugate strong acid) e. H₂SO₄ (conjugate acid), SO₄⁻² (conjugate base) ; f. No conjugate acid either base; g. H₂S (conjugate acid), S⁻² (conjugate base);

h. H₄N₂ (conjugate base)

Explanation:

a. OH⁻ + H⁺ ⇄ H₂O

The hydroxide acts like a Bronsted Lory base, so it can catch a proton. Water will be the conjugate acid.

b. H₂O, is an amphoterus compound. It can act as an acid or a base. If it is a base, the conjugate acid is the H₃O⁺. If it is an acid, the conjugate base is the OH⁻.

c. HCO₃⁻ + H⁺ ⇄ H₂CO₃

HCO₃⁻ + H₂O ⇄ CO₃⁻² + H₃O⁺

The bicarbonate is also amphoteric. When it catches the proton, the carbonic acid is the conjugate acid, cause it works as a base.

When the HCO₃⁻ (acid) release the proton, the conjugate base is the carbonate.

d. Ammonia is a weak base, so the conjugate strong acid is the ammonium.

NH₃ + H₂O ⇄ NH₄⁺ + OH⁻

e. Another amphoteric compound. The acid sulfate acts an acid and a base.

(like bicarbonate). When it is a base, the conjugate acid is the sulfuric acid, when it is an acid, the conjugate base is the sulfate.

HSO₄⁻ + H₂O ⇄ SO₄⁻² + H₃O⁺

HSO₄⁻ + H⁺ ⇄ H₂SO₄

f. H₂O₂ does not recieve H⁺ or OH⁻, and it does not release H⁺. It is a neutral compound and it doesn't act as a base or acid.

g. HS⁻ is amphoterous.

HS⁻ + H⁺ ⇄ H₂S

HS⁻ + H₂O ⇄ S⁻² + H₃O⁺

Same case as bicarbonate or acid sulfate.

h. H₅N₂⁺ + H₂O ⇄ H₄N₂ + H₃O⁺

Hidrazinium acts an acid, so, the conjugate base will be the hidrazine.

3 0

4 years ago

How does density determine whether an object will float?

Kipish [7]

If the object is denser then the substance it's in, it will sink. If the object is less dense than the substance, it will float.

7 0

3 years ago

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What holds the two parts of a metal together?<br>S<br>E<br>A

lutik1710 [3]

Answer: The metal is held together by the strong forces of attraction between the positive nuclei and the delocalized electrons (The Electron Sea Model.

Explanation: I hope that helped!

8 0

3 years ago

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