The atomic masses of 20Ne (90.48 percent), 21Ne (0.27 percent), and 22Ne (9.25 percent) are 19.9924356, 20.9938428, and 21.9913831 amu, respectively. Calculate the average atomic mass of neon. The percentages in parentheses denote the relative abundance

Answer:

The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.

Explanation:

The hydrochloric acid and sodium carbonate reaction was exothermic that caused the pressure to decrease. The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.

In exothermic reactions, energy is produced in the form of heat or light.

Answer:

Purple light.

Yellow light.

Explanation:

Answer: The percent yield of the reaction is 77.0 %

Explanation:

[tex]2Pb+O_2\rightarrow 2PbO[/tex]

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

[tex]\text{Number of moles of lead}=\frac{451.4g}{207.2g/mol}=2.18moles[/tex]

[tex]\text{Number of moles of lead oxide}=\frac{374.7g}{223.2g/mol}=1.68moles[/tex]

According to stoichiometry:

2 moles of [tex]Pb[/tex] produces = 2 moles of [tex]PbO_2[/tex]

2.18 moles of [tex]Pb[/tex] is produced by=[tex]\frac{2}{2}\times 2.18=2.18moles[/tex] of [tex]PbO_2[/tex]

Mass of [tex]PbO_2[/tex] =[tex]moles\times {\text {Molar mass}}=2.18\times 223.2g/mol=486.6[/tex]

percent yield =[tex]\frac{374.7g}{486.6g}\times 100=77.0\%[/tex]

Answer: The monoatomic ions formed by bromine and rubidium are [tex]Br^-[/tex] and [tex]Rb^+[/tex] respectively.

Explanation:

When an atom accepts an electron negative charge is created on atom and is called as anion.  When atom loses an electron positive charge is created on atom and is called as cation.

The atomic number of bromine and rubidium is 35 and 37 respectively. So, the number of electrons is equal to 35 and 37 respectively. Bromine will gain one electron and rubidium will lose one electron to attain stable electronic configuration to form [tex]Br^-[/tex] and [tex]Rb^+[/tex] respectively.

[tex]Br:35:1s^22s^22p^63s^23p^64s^23d^{10}4p^5[/tex]

[tex]Br^-:36:1s^22s^22p^63s^23p^64s^23d^{10}4p^6[/tex]

[tex]Rb:37:1s^22s^22p^63s^23p^64s^23d^{10}4p^63s^1[/tex]

[tex]Rb^+:36:1s^22s^22p^63s^23p^64s^23d^{10}4p^6[/tex]

Answer:

15 cents where im from

Explanation:

This follows a simple conversion technique. Basically what the question is trying to say here is to convert 29.1 inHg to mmHg. 1 inHg is equal to 25.4 mmHg so 29.1 inHg would be equal to [tex]25.4 * 29.1[/tex] which when evaluated turns out to be: [tex]739.14[/tex]. :D

The pressure will be 739.14 mm Hg.

The SI unit measuring pressure would be the pascal, which measures the force of each unit area of the surface.

Calculation of pressure

It is known that 1inHg = 25.4 mm Hg.

Hence, the pressure = 25.4 × 29.1 = 739.14 mm Hg

Therefore, the pressure will be 739.14 mm Hg.

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Answer:

Explanation:B ice melting is a phiyscal change and the mass of the substance remains the same

Answer:

b

Explanation:

Answer:

for electricity, watts as in back to the future "1.21 jigga watts"!

Explanation:

Answer:

Left over mass of hydrogen = 0.06 g

Mass of HCl produced = 12.41 g

Explanation:

Given data:

Mass of H₂ = 0.40 g

Mass of Cl₂ = 12.35 g

Mass of left over reactant = ?

Mass of HCl produced = ?

Solution:

Chemical equation:

H₂ + Cl₂    →     2HCl

Number of moles of H₂:

Number of moles = mass / molar mass

Number of moles = 0.40 g/ 2 g/mol

Number of moles = 0.2 mol

Number of moles of Cl₂:

Number of moles = mass / molar mass

Number of moles = 12.35 g/ 71 g/mol

Number of moles = 0.17 mol

Now we will compare the moles of HCl with H₂ and Cl₂.

                     H₂             :            HCl

                      1               :               2

                   0.2              :           2×0.2 = 0.4

                     Cl₂             :             HCl

                      1               :              2

                    0.17           :            2 × 0.17 = 0.34

Chlorine is limiting reactant.

Mass of HCl produced:

Mass = number of moles × molar mass

Mass = 0.34 mol × 36.5 g/mol

Mass = 12.41 g

Leftover mass of hydrogen:

                          Cl₂               :               H₂

                            1                :                 1

                           0.17            :             0.17

Number of moles of H₂ react with Cl₂  are 0.17.

Moles remain unreacted = 0.2 - 0.17 = 0.03 mol

Mass left over:

Mass = number of moles × molar mass

Mass = 0.03 mol × 2 g/mol

Mass = 0.06 g

The sum of the mass of HCl produced plus the mass of left over reactants is:

Mass of hydrogen = 0.06 g

Mass of HCl  = 12.41 g

Given:

Mass of H₂ = 0.40 g

Mass of Cl₂ = 12.35 g

Mass of left over reactant = ?

Mass of HCl produced = ?

Number of moles of H₂:

Number of moles = mass / molar mass

Number of moles = 0.40 g/ 2 g/mol

Number of moles = 0.2 mol

Number of moles of Cl₂:

Number of moles = mass / molar mass

Number of moles = 12.35 g/ 71 g/mol

Number of moles = 0.17 mol

The moles of HCl with H₂ and Cl₂.                

  H₂             :            HCl              

     1              :               2          

     0.2          :           2×0.2 = 0.4                

    Cl₂             :             HCl            

        1             :              2          

       0.17         :          2 × 0.17 = 0.34

The chlorine is limiting reactant.

Mass of HCl produced:

Mass = number of moles × molar mass

Mass = 0.34 mol × 36.5 g/mol

Mass = 12.41 g

Leftover mass of hydrogen:                

         Cl₂               :               H₂            

              1             :                 1          

               0.17       :             0.17

Number of moles of H₂ react with Cl₂  are 0.17.

Moles remain unreacted = 0.2 - 0.17 = 0.03 mol

Mass left over:

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Answer:

True, it undergoes a physical change.

Explanation:

A physical change is a change that does not change the chemical makeup of a material. This includes altering its shape.

Answer: Spun yarn is made by twisting staple fibers together

To make a cohesive thread Or “single”. Twisting fibers, into yarn in the process called spinning can be dated back to the upper Paleolithic. Yarn spinning was one of the first processes to be industrialized.

Explanation:

Answer:

349.22°C

Explanation:

Let the final temperature of the two pieces of metal be x.

Now, the warmer metal which is C u reduces from 475°C to x. Thus Δt for C u is; Δt1 = 475 - x.

The cooler metal Cr increases in temperature from 265°C to x. Thus, it's change in temperature is Δt for Cr is; Δt2 = x - 265.

Now from conservation of energy, the amount of energy leaving the C u metal is equal to the amount of energy entering the Cr metal.

Thus;

q_lost = q_gain

Where;

q_lost = m1•c1•Δt1

q_gained = m2•c2•Δt2

Now, c1 & c2 are the specific heat capacity of C u and Cr respectively.

From online tables, c1 = 0.385 J/g°C and c2 = 0.46 J/g°C

We are given;

m1 = 12g and m2 = 15g

Thus;

12 × 0.385 × (475 - x) = 15 × 0.46 × (x - 265)

2194.5 - 4.62x = 6.9x - 1828.5

6.9x + 4.62x = 2194.5 + 1828.5

11.52x = 4023

x = 4023/11.52

x = 349.22°C