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Ann [662]
2 years ago
11

How many molecules are in 42.3g sample of water

Chemistry
1 answer:
Helga [31]2 years ago
5 0

Answer:

The number of molecules is 1.4140*10^24 molecules

Explanation:

To know the number of molecules, we need to determine how many moles of water we have, water has molar mass of 18.015g/mol

This means that one mole of water molecules has a mass of 18.015g.

42.3g * 1 mole H2O/18.015g

= 2.3480 moles H2O

We are using avogadros number to find the number of molecules of water

2.3480 H2O * 6.022*10^ 23moles/ 1mole of H2O

That's 2.3480 multiplied by 6.022*10^23 divided by 1 mole of H2O

Number of molecules = 1.4140 *10^24 molecules

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The isotope 64Cu has t1/2 of 12.7 hours. If the initial concentration of this isotope in an aqueous solution is 845 ppm, what wi
Kisachek [45]

Answer:

A = 679.2955 ppm

Explanation:

In this case, we already know that 64Cu has a half life of 12.7 hours. The expression to use to calculate the remaining solution is:

A = A₀ e^-kt

This is the expression to use. We have time, A₀, but we do not have k. This value is calculated with the following expression:

k = ln2 / t₁/₂

Replacing the given data we have:

k = ln2 / 12.7

k = 0.0546

Now, let's get the concentration of Cu:

A = 845 e^(-0.0546*4)

A = 845 e^(-0.2183)

A = 845 * 0.8039

A = 679.2955 ppm

This would be the concentration after 4 hours

7 0
2 years ago
A sample of solid sodium hydroxide, weighing 13.20 grams is dissolved in deionized water to make a solution. What volume in mL o
igomit [66]
<h3>Answer:</h3>

702 mL

<h3>Explanation:</h3>

We are given;

The mass of sodium hydroxide  = 13.20 g

Molarity of H₂SO₄ = 0.235 M

We are required to calculate the volume of the acid required to neutralize the solution of NaOH

<h3>Step 1: Balanced equation for the reaction</h3>

The equation for the reaction between H₂SO₄ and NaOH is given by;

2NaOH(aq) + H₂SO₄(aq) → Na₂SO₄(aq) + 2H₂O(l)

<h3>Step 2: Calculate the number of moles of NaOH</h3>

Number of moles is given by dividing mass by molar mass

Molar mass of NaOH = 40.0 g/mol

Therefore;

Number of moles of NaOH = 13.20 g ÷ 40 g/mol

                                             = 0.33 moles of NaOH

<h3>Step 3: Calculate the number of moles of H₂SO₄ used during the reaction </h3>

From the equation 2 moles of NaOH reacts with 1 mole H₂SO₄

Therefore, the mole ratio of NaOH : H₂SO₄ is 2 : 1

Thus, number of moles of H₂SO₄ = Moles of NaOH ÷ 2

                                                       = 0.33 moles ÷ 2

                                                       = 0.165 moles

<h3>Step 4: Calculate the volume of the H₂SO₄</h3>

Molarity refers to the concentration of a solution in moles per liter

Molarity = Number of moles ÷ Volume

Rearranging the formula;

Volume = Number of moles ÷ Molarity

            = 0.165 moles ÷ 0.235 M

            = 0.702 L

           = 702 mL

Therefore, the volume of 0.235 M acid solution required is 702 ml

8 0
2 years ago
Which isolated gaseous atom has a total of five electrons occupying spherically shaped orbitals?
Andre45 [30]
Let's find the electron configuration of each atom


Atom      atomic number                electron configuration

Bo            5                                    1s2 2s2 2p
F              9                                    1s2 2s2 2p5 
Na          11                                    1s2 s2 2p6 3s
K            19                                    1s2 2s2 2p6 3s2 3p6 4s      


The spherically shaped orbitals are the s orbitals.



You can se in the table that I wrote above that sodium has 2 electrons at 1s, 2 electrons at 2s and 1 electron at 3s orbitals, that is a total of five electrons at s (spherically shaped orbtials).



So the answer is the option A) sodium.
3 0
2 years ago
Benzene, C6H6, reacts with oxygen, O2, to form CO2 and H2O. How much O2 is required for the complete combustion of 1.0 mol C6H6?
Vsevolod [243]
C6H6 + 02 forms CO2 + H20
Complete with factors to stabilize
C6H6 + 15/2 O2 forms 6 CO2 + 3 H2O
You take away only the info you need
C6H6 15/2 O2
1 mol 15/2 or 7,5 mol

15/2 or 7,5 mol of O2 are required.

;)
4 0
2 years ago
Read 2 more answers
When filling a burette for a titration, adjust the burette so that______, preferably over a sink. Then,_______to add the titrant
artcher [175]

Answer:

Explanation:

When filling a burette for a titrant, adjust the burette so that the opening is near or below the eye leve preferably over the sink.

Then, use a funnel to add the titrant into the burette.

The titrant should be filled almost to the zero mark.

6 0
2 years ago
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