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2 years ago

12

Carbon -11 is a radioactive isotope of carbon. It’s half life is 20 minutes. What amount of the initial mass of 70.0g of C -11 a

toms in a sample will be left after 80 minutes

1 answer:

dusya [7]2 years ago

6 0

Answer:

4.38g

Explanation:

70.0/2 = 35g - 20 mins

35/2 = 17.5g - 40 mins

17.5/2 = 8.75g - 60 mins

8.75/2 = 4.375g - 80 mins

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Which of the following is not used when analyzing and evaluating scientific explanations?

LiRa [457]

C. Preconceived ideas

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2 years ago

Given one mole of each substance, which of the following will produce the FEWEST particles in aqueous solution? 1. sodium nitrat

svlad2 [7]

<u>Answer:</u> The substance that produces fewest particles is $CH_2Cl_2$

<u>Explanation:</u>

Ionization reaction is defined as the reaction in which an ionic compound dissociates into its ions when dissolved in aqueous solution.

Covalent compounds do not dissociate into ions when dissolved in aqueous solution.

For the given options:

<u>Option 1:</u> Sodium nitrate

The chemical formula of sodium nitrate is $NaNO_3$

The ionization reaction for the given compound follows:

$NaNO_3(aq.)\rightarrow Na^+(aq.)+NO_3^-(aq.)$

This produces in total of 2 ions.

<u>Option 2:</u> $CH_2Cl_2$

The given compound is a covalent compound and do not dissociate into its ions. It remains as such as a single unit.

<u>Option 3:</u> $K_2SO_4$

The chemical name for the given compound is potassium sulfate.

The ionization reaction for the given compound follows:

$K_2SO_4(aq.)\rightarrow 2K^+(aq.)+SO_4^{2-}(aq.)$

This produces in total of 3 ions.

<u>Option 4:</u> Sodium phosphate

The chemical formula of sodium phosphate is $Na_3PO_4$

The ionization reaction for the given compound follows:

$Na_3PO_4(aq.)\rightarrow 3Na^+(aq.)+PO_4^{3-}(aq.)$

This produces in total of 4 ions.

Hence, the substance that produces fewest particles is $CH_2Cl_2$

3 0

2 years ago

This quantity tells me how many grams of a substance is in one mole of a substance: mole ratio molar mass avogadro's number

galben [10]

I am not completely sure what your question is, but I think you are asking about the molar mass? It is a mole conversion. For example, if you start with atoms and want grams, you would need to get rid of the atoms unit first then get rid of the mols unit: so you would have to multiply it by (1 mol / Avogadro's number) X (molar mass / 1 mol) = this is the conversion factor that gives you grams. I hope this helped!
Have a fantastical day,
Em

3 0

2 years ago

Read 2 more answers

You must make 1 L of 0.2 M acetic acid (CH3COOH). All you have available is concentrated glacial acetic acid (assay value, 98%;

Sergeu [11.5K]

Answer:

The correct answer is "11.44 ml".

Explanation:

Molarity,

= 0.2 M

Density,

= 1.05 g/ml

Volume,

= 1 L

As we know,

⇒ $Molarity=\frac{No. \ of \ moles }{Volume \ of \ solution}$

or,

⇒ $No. \ of \ moles=Molarity\times Volume$

On putting the values, we get

⇒ $=0.2\times 1$

⇒ $=0.2 \ moles$

Now,

⇒ $No. \ of \ moles=\frac{Mass \ taken}{Molecular \ mass}$

or,

⇒ $Mass \ taken=No. \ of \ moles\times Molecular \ mass$

⇒ $=0.2\times 60.05$

⇒ $=12.01 \ gram$

hence,

⇒ $Density= \frac{Mass }{Volume}$

or,

⇒ $Volume=\frac{Mass}{Density}$

⇒ $=\frac{12.01}{1.05}$

⇒ $=11.44 \ ml$

7 0

2 years ago

Calcula el pH de las siguientes sustancias formadas durante una erupción volcánica:

Virty [35]

<em>Calculate the pH of the following substances formed during a volcanic eruption: </em>

<em>• Acid rain if the [H +] is 1.9 x 10-5 </em>

<em>• Sulfurous acid if [H +] = 0.10 </em>

<em>• Nitric acid if [H +] = 0.11</em>

<em />

<h3>Further explanation </h3>

pH is the degree of acidity of a solution that depends on the concentration of H⁺ ions. The greater the value the more acidic the solution and the smaller the pH.

pH = - log [H⁺]

pH acid rain

$\tt pH=-log[1.9\times 10^{-5}]\\\\pH=5-log1.9\\\\pH=4.72$

pH Sulfurous acid

$\tt pH=-log[10^{-1}]\\\\pH=1$

pH Nitric acid

$\tt pH=-log[11\times 10^{-2}]\\\\pH=2-log~11=0.959$

8 0

2 years ago