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kondor19780726 [428]
3 years ago
6

Which of these is NOT a physical change?

Chemistry
1 answer:
alexdok [17]3 years ago
6 0

Answer:

C. Magnetization of iron

Explanation:

This is a chemical change and cannot be undone by physical means therefore it isn't a physical change

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Which of the following atoms has the largest atomic radius? Provide an explanation
trapecia [35]

Answer:

d Rubidium

Explanation:

The atomic radius of an atom is the distance from the center of the nucleus to its outermost electron.

The atomic radius of elements varies in the periodic table, it increases as you go down in a group and decreases along the period from left to right.  

All the elements listed: Hydrogen, Sodium, Lithium and Rubidium belong to the same group in the periodic table (group 1), Since atomic radius increases from top to bottom in a group, Rubidium has the largest atomic radius.

4 0
3 years ago
How much energy must be removed from a 125 g sample of benzene (molar mass= 78.11 g/mol) at 425.0 K to liquify the sample and lo
riadik2000 [5.3K]

Answer : The energy removed must be, -67.7 kJ

Solution :

The process involved in this problem are :

(1):C_6H_6(g)(425.0K)\rightarrow C_6H_6(g)(353.0K)\\\\(2):C_6H_6(g)(353.0K)\rightarrow C_6H_6(l)(353.0K)\\\\(3):C_6H_6(l)(353.0K)\rightarrow C_6H_6(l)(335.0K)

The expression used will be:

\Delta H=[m\times c_{p,g}\times (T_{final}-T_{initial})]+m\times \Delta H_{vap}+[m\times c_{p,l}\times (T_{final}-T_{initial})]

where,

\Delta H = heat released by the reaction = ?

m = mass of benzene = 125 g

c_{p,g} = specific heat of gaseous benzene = 1.06J/g^oC

c_{p,l} = specific heat of liquid benzene = 1.73J/g^oC

\Delta H_{vap} = enthalpy change for vaporization = 33.9kJ/mole=33900J/mole=\frac{33900J/mole}{78.11g/mole}J/g=434.0J/g

Molar mass of benzene = 78.11 g/mole

Now put all the given values in the above expression, we get:

\Delta H=[125g\times 1.06J/g.K\times (353.0-(425.0))K]+125g\times -434.0J/g+[125g\times 1.73J/g.K\times (335.0-353.0)K]

\Delta H=-67682.5J=-67.7kJ

Therefore, the energy removed must be, -67.7 kJ

4 0
2 years ago
Which conversion factor is needed to solve the following problem?
77julia77 [94]
It is going to be  <span>Molar Volume
</span><span>3H2 + N2 --> 2NH3
</span><span> 54.1L*22.4 L/mol H2 , you can find mol of H2, then mol of NH3, and then L of NH3</span>
5 0
3 years ago
4. When 1.00 L of 1.00 M Ba(NO3)2 solution at 25.0˚C is mixed with 1.00 L of 1.00 M Na2SO4 solution at 25.0˚C in a calorimeter,
myrzilka [38]

Answer:

The final temperature of the mixture is 28.11 °C

Explanation:

Step 1: Data given

Volume of 1.00 M Ba(NO3)2 = 1.00 L

Temperature = 25.0 °C

Volume of 1.00 M Na2SO4 = 1.00 L

enthalpy change is – 26 kJ per mol BaSO4

The specific heat of water is 4.18 J/g ·˚C

the density of water is 1.00 g/mL

Step 2: The balanced equation

Ba(NO3)2(aq) + Na2SO4(aq) → 2NaNO3(aq) + BaSO4(s)

Step 3: Calculate the total volume

Total volume = 1.00 L + 1.00 L = 2.00 L = 2000 mL

Step 4: Calculate mass

Mass = volume * density

Mass = 2000 mL * 1g/mL

Mass = 2000 grams

Step 5: Calculate moles BaSO4 formed

For 1 mol Ba(NO3)2 we need 1 mol Na2SO4 to produce 1 mol BaSO4

There is no limiting reactant, both Ba(NO3)2 and Na2SO4 will be completely be consumed (1 mol). We'll have 1.0 mol of BaSO4 produced.

Step 6: Calculate Q

Q = - ΔH

ΔH is negative so the reaction is exothermic, what means the temperature increases

Q is always positive, so Q = 26kJ = 26000 J

Step 6: Calculate the heat transfer

Q= m*c*ΔT

⇒with Q = the heat transfer = TO BE DETERMINED

⇒with m =the mass of the solution = 2000 grams

⇒with c= the specific heat of the solution = 4.18 J/g°C

⇒with ΔT = the change of temperature = T2 - T1 = T2 - 25.0

26000 = 2000 * 4.18 * (T2 - 25.0 °C)

3.11 = T2 - 25.0 °C

T2 = 25.0 + 3.11 °C

T2 = 28.11 °C

The final temperature of the mixture is 28.11 °C

7 0
3 years ago
Hydrogen gas is collected over water at 21 degrees Celsius. At 21 degrees Celsius the vapor pressure of water is 18.7 torr. If t
Alinara [238K]

Answer : The pressure of hydrogen gas is, 739.3 torr

Explanation :

As we are given:

Vapor pressure of water = 18.7 torr

Barometric pressure = 758 torr

Now we have to calculate the pressure of hydrogen gas.

Pressure of hydrogen gas = Barometric pressure - Vapor pressure of water

Pressure of hydrogen gas = 758 torr - 18.7 torr

Pressure of hydrogen gas = 739.3 torr

Therefore, the pressure of hydrogen gas is, 739.3 torr

3 0
3 years ago
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