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3 years ago

Why don’t the trees spontaneously catch fire and burn all the time? Why don’t the fires stop immediately as soon as they start?

Chemistry

1 answer:

algol133 years ago

7 0

Answer:

Both of these phenomena is due to the ignition temperature.

Explanation:

Trees don't spontaneously catch fire because there is a temperature above which materials combust. This is called the "ignition temperature." This temperature must be reached before the trees will ignite, and the external condition does not always harbor such high temperature.

Fires don't stop immediately because, while some parts of the flame has cooled down sufficiently below the ignition temperature, other parts of the flame have not. It takes time for all the part of the flame to cool down below ignition temperature for the burning to stop.

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When a aqueous solution of a certain acid is prepared, the acid is dissociated. Calculate the acid dissociation constant of the

stepan [7]

<h2> $K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$ </h2>

Explanation:

When an aqueous solution of a certain acid is prepared it is dissociated is as follows-

${\displaystyle {\ce {HA$ ⇄ ${H^+}+{A^{-}}} }}$

Here HA is a protonic acid such as acetic acid, $CH_3COOH$

The double arrow signifies that it is an equilibrium process, which means the dissociation and recombination of the acid occur simultaneously.

The acid dissociation constant can be given by -

$K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$

The reaction is can also be represented by Bronsted and lowry -

$\\{\displaystyle {\ce {{HA}+ H_2O}$ ⇄ $[H_3O^+] [A^-]$

Then the dissociation constant will be

$K_a$ = $\dfrac{[H_3O^{+}] [A^{-}]}{[HA]}$

Here, $K_a$ is the dissociation constant of an acid.

6 0

3 years ago

What is the concentration of a solution with a volume of 2.5 liters containing 600 grams of calcium phosphate?

trapecia [35]

Answer:

1.12M

Explanation:

Given parameters:

Volume of solution = 2.5L

Mass of Calcium phosphate = 600g

Unknown:

Concentration = ?

Solution:

Concentration is the number of moles of solute in a particular solution.

Now, we find the number of moles of the calcium phosphate from the given mass;

Formula of calcium phosphate = Ca₃PO₄

molar mass = 3(40) + 31 + 4(16) = 215g/mol

Number of moles of Ca₃PO₄ = $\frac{600}{215}$ = 2.79moles

Now;

Concentration = $\frac{Number of moles }{volume }$

Concentration = $\frac{2.79}{2.5}$ = 1.12M

7 0

3 years ago

Which of the following is a safety precaution for handling radioactive material?

omeli [17]

C.) remove yourself from the radiation every 15 mins to prevent accumulation

7 0

2 years ago

Read 2 more answers

Giving brain thing

lana66690 [7]

I’m pretty sure the answer is C

5 0

3 years ago

Nitrogen dioxide is used industrially to produce nitric acid, but it contributes to acid rain and photochemical smog. What volum

zhuklara [117]

Answer:

The volume of nitrogen oxide formed is 35.6L

Explanation:

The reaction of nitric acid with copper is:

Cu(s) + 4HNO₃ → Cu(NO₃)₂ + 2NO₂(g) + 2H₂O(l)

Moles of copper are:

$4.95cm^3\frac{8.95g}{1cm^3} \frac{1mol}{63.55g} = 0.697 moles$

Moles of nitric acid are:

$230mL\frac{1.42g}{mL} \frac{68g}{100g} \frac{1mol}{63.01g}=3.52moles$

As 1 mol of Cu reacts with 4 moles of HNO₃:

0.697 mol Cu × (4mol HNO₃ / 1mol Cu) = 2.79 moles of HNO₃ will react. That means Cu is limiting reactant.

Moles of NO₂ produced are:

0.697 mol Cu × (2mol NO₂ / 1mol Cu) = <em>1.394 moles of NO₂</em>

Using PV = nRT

<em>Where P is pressure (735torr / 760 = 0.967atm); n are moles (1.394mol); R is gas constant (0.082atmL/molK); T is temperature (28.2°C + 273.15 = 301.35K). </em>

Thus, volume is:

V = nRT / P

V = 1.394mol×0.082atmL/molK×301.35K / 0.967atm

V = 35.6L

<em>The volume of nitrogen oxide formed is 35.6L</em>

3 0

3 years ago