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4 years ago

Why is it important to keep th naoh solution covered at all times?

1 answer:

Ber [7]4 years ago

4 0

<span> It is important to keep the NaOH solution covered at all time because sodium hydroxide is a very good remover of Carbon dioxide from the air means sodium hydroxide absorbs the carbon dioxide from the air react with that so the concentration of your solution will also change if you uncover the NaOH.
The following reaction occurs when sodium hydroxide reacts with carbon dioxide;
</span><span>2 NaOH(aq) + CO2(g) --> Na3CO3(aq) + H2O(l) </span>

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What measurements are used to calculate the density of a given object?

professor190 [17]

Answer:

Density = $\frac{Mass}{Volume}$

Explanation:

Density equals mass divided by volume.

Density often has units of grams per cubic centimeter (g/cm3). Remember, grams is a mass and cubic centimeters is a volume (the same volume as 1 milliliter).

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3 years ago

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The radius of a hydrogen atom is 37 pm and its mass is 1.67 × 10-24 g. What is the density of the atom in grams per cubic centim

RoseWind [281]

Answer:

V = 4/3 * 3.1416 * (37x10-10)3

V = 2.12x10-25 cm3

d = m/V

d = 1.67x10-24 / 2.12x10-25 = 7.87 g/cm3

The difference in temperature, let's convert F to ºC:

ºC = -80-32/1.8 = -62.22 ºC

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4 years ago

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An igneous rock originally has 3 grams of uranium 238 in it. When dated the rock only contains 1.8 grams. What are the parent an

castortr0y [4]

Answer :

The parent and daughter concentrations (in percentages) is, 60 % and 40 % respectively.

The age of rock is $3.32\times 10^9\text{ years}$

Explanation :

First we have to calculate the parent and daughter concentrations (in percentages).

$\text{Parent concentrations}=\frac{1.8g}{3g}\times 100=60\%$

and,

$\text{Daughter concentrations}=\frac{(3-1.8)g}{3g}\times 100=40\%$

As we know that, the half-life of uranium-238 = $4.5\times 10^9$ years

Now we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{4.5\times 10^9\text{ years}}$

$k=1.54\times 10^{-10}\text{ years}^{-1}$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $1.54\times 10^{-10}\text{ years}^{-1}$

t = time passed by the sample = ?

a = initial amount of the reactant = 3 g

a - x = amount left after decay process = 1.8 g

Now put all the given values in above equation, we get

$t=\frac{2.303}{1.54\times 10^{-10}}\log\frac{3}{1.8}$

$t=3.32\times 10^9\text{ years}$

Therefore, the age of rock is $3.32\times 10^9\text{ years}$

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3 years ago

Which of the following is the best definition of convection?

lara [203]

<span>a) movement of heat through space </span>

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3 years ago

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The pH of a 0.016-M aqueous solution of p-toluidine<br> (CH3C6H4NH2) is 8.60. Calculate Kb.

harkovskaia [24]

From the calculations performed, the Kb of the reaction is 9.9 * 10^-10

The term Kb refers to the base dissociation constant of a solution. We have the following information from the question;

pH of the solution = 8.60

concentration of p-toluidine = 0.016-M

Recall that pOH = 14 - pH

pOH = 14 - 8.60 = 5.4

[OH] = Antilog (-5.4) = 3.98 * 10^-6 M

We have to set up the ICE table;

CH3C6H4NH2(aq) + H2O(l) ⇄ CH3C6H4NH3^+(aq) + OH^-(aq)

I 0.016 0 0

C -x +x +x

E 0.016 - x 3.98 * 10^-6 3.98 * 10^-6

Hence;

Kb = [3.98 * 10^-6]^2/[0.016 - 3.98 * 10^-6]

Kb = 9.9 * 10^-10

Learn more about Kb: brainly.com/question/12726841

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2 years ago