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Orlov [11]
2 years ago
11

A scientist has 207.45g of H2O in a beaker. How many water molecules are in the beaker?

Chemistry
1 answer:
Tasya [4]2 years ago
4 0

Answer:

6.94 x 10²⁴molecules

Explanation:

Given parameters:

Mass of water  = 207.45g

Unknown:

Number of molecules  = ?

Solution:

To solve this problem, we must understand:

      1 mole of a substance  contains 6.02 x 10²³ molecules

Now, first find the number of moles of water;

 Number of moles  = \frac{mass}{molar mass}  

 Molar mass of water  = 2(1) + 16  = 18g/mol

  Number of moles  = \frac{207.45}{18}   = 11.53moles

So;

          1 mole of a substance  contains 6.02 x 10²³ molecules

       11.53moles of carbon dioxide will contain 11.53 x  6.02 x 10²³

                                                                 = 6.94 x 10²⁴molecules

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PH & POH
Mashcka [7]

Answer:

<h2>4.0 </h2>

Explanation:

The pH of a solution can be found by using the formula

pH = - log [ { H}^{+}]

From the question we have

ph =  -  log(9.25 \times  {10}^{ - 5} )  \\  = 4.03385

We have the final answer as

<h3>4.0</h3>

Hope this helps you

5 0
2 years ago
Please help!!! DUE IN 10 minutes
NARA [144]

Answer:

90

   Th

    232.04

Explanation:

90 - atomic number

  Th - element symbol

    232.04 - atomic mass

4 0
2 years ago
Based on patterns in the periodic table, which ion has a stable valence electron configuration?
kifflom [539]

The ions of Noble gases, <em>group VIII</em> elements have a full octet configuration on their outermost shell and as such are highly stable.

The periodic table is a systematic arrangement of elements in order of their atomic numbers into a set of 8 columns each called groups and a set of 7 rows each called a period.

Elements are arranged in different groups according to the number of Valence electrons they have.

  • For instance, elements in the group I of the periodic table are highly electropositive and as such are highly reactive.

The same is evident in group 7 elements are highly electronegative and have high electron affinity and as such are unstable and reactive.

  • However, Noble gases, <em>group VIII</em> elements have a full octet configuration on their outermost shell and as such are highly stable.

Consequently, the <em>Noble gases ion</em> has a stable Valence electron configuration.

Read more:

brainly.com/question/5336231

4 0
2 years ago
A 200.0 mL solution of 0.40 M ammonium chloride was titrated with 0.80 M sodium hydroxide. What was the pH of the solution after
choli [55]

Answer:

9.25

Explanation:

Let first find the moles of NH_4Cl and NaOH

number of moles of NH_4Cl = 0.40  mol/L × 200 ×  10⁻³L

= 0.08 mole

number of moles of NaOH = 0.80  mol/L × 50 ×  10⁻³L

= 0.04 mole

The equation for the reaction is expressed as:

NH^+_{4(aq)} \ + OH^-_{(aq)} ------> NH_{3(g)} \ + H_2O_{(l)}

The ICE Table is shown below as follows:

                            NH^+_{4(aq)} \ + OH^-_{(aq)} ------> NH_{3(g)} \ + H_2O_{(l)}

Initial (M)              0.08            0.04                            0

Change (M)         - 0.04          -0.04                          + 0.04

Equilibrium (M)      0.04             0                                0.04

K_a*K_b = 10^{-14} \ at \ 25^0C

K_a = \frac{10^{-14}}{K_b}

K_a = \frac{10^{-14}}{1.76*10^{-5}}

K_a= 5.68*10^{10}

pK_a = - log \ (K_a)

pK_a = - log \ (5.68*10^{-10})

pK_a = 9.25

pH = pKa + \ log (\frac{HB}{HA} )   for buffer solutions

pH = pKa + \ log (\frac{moles \ of \ base }{ moles\ of \ acid} ) since they are in the same solution

pH = 9.25 + \ log (\frac{0.04 }{ 0.04} )

pH = 9.25

8 0
2 years ago
What is 190 K in degrees Celsius? Show your work for full credit.
saveliy_v [14]

Answer:

-83.15

Explanation:

190K − 273.15 = -83.15°C

3 0
2 years ago
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