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tangare [24]
2 years ago
10

A 37.2-g sample of lead (Pb) pellets at 20°C is mixed with a 62.7-g sample of lead pellets at the same temperature. What are th

e final mass, temperature, and density of the combined sample? The density of Pb at 200C is 11.35 g/cm^3.
Chemistry
1 answer:
Vesnalui [34]2 years ago
8 0

Answer:

Mass of sample is 99.9 g, density of ample is 11.35 g/cm^{3} and temperature of sample is 20^{0}\textrm{C}

Explanation:

Mass is an additive property. Therefore mass of combined sample is summation of masses of two pellets.

Mass of combined sample = (37.2+62.7) g = 99.9 g

Density is an intensive property. Therefore density of combined sample of lead will be same as with density of Pb.

Density of combined sample = 11.35 g/cm^{3}

Temperature is an intensive property. Therefore temperature of combined sample of lead will be same as with individual pellets.

temperature of combined sample = 20^{0}\textrm{C}

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Each response gives a pair of solutions. which pair of solutions should conduct electrical current equally well? 1. 0.10 m nh3 a
Crazy boy [7]

Answer : The correct answer is option 2 : 0.10 M NaCl and 0.10 M NaClO₄

Explanation :

Solutions are classified into 3 categories.

1) Strong electrolytes : These are the solutions that dissociate completely forming ions . They are good conductors of electricity.

Example : All strong acids, bases and the salts made by strong acid/base are strong electrolytes .

2) Weak electrolytes : These substances do not dissociate completely thereby forming fewer ions. They are weak conductors of electricity.

3) Non electrolytes : These are the substances that do not dissociate at all. They do not form ions in aqueous medium. They are bad conductors of electricity.

Let us take a look at the given options and find out what type of solution do we have .

Option 1 : NH₃ is a weak electrolyte whereas NH₄Cl is a strong electrolyte bcause NH₄Cl is made by combination of NH₃ and HCl ( HCl is a strong acid)

Therefore NH₃ would carry electricity less efficiently than NH₄Cl.

Option 2 : Both NaCl and NaClO₄ are strong electrolytes. Therefore they will conduct electrical current equally well

Option 3 : NaNO₃ is a strong electrolyte but HNO₂ is a weak electrolyte. Therefore they will not carry the current equally

Therefore the correct option is option 2

3 0
2 years ago
Calculate the energy difference for a transition in the paschen series for a transition from the higher energy shell n=4. expres
Troyanec [42]
Electrons are orbiting around the nucleus in a specific energy level as described in Bohr's atomic model. There are 7 energy levels all in all; 1 being the strongest and nearest to the nucleus, and 7 being the weakest and farthest away from the nucleus. Electron can transfer from one energy level to another. If it increases energy, it absorbs energy. If it goes down an energy level, it emits energy in the form of light. This light can be measure in wavelength through the Rydberg equation:

1/λ =R(1/n₁² -1/n₂²), where
λ is the wavelength
R is the Rydberg constant equal to 1.097 × 10⁻7<span> per meter
n</span>₁ and n₂ are the energy levels such that n₂>n₁

In the Paschen series is an emission spectrum of hydrogen when the energy level is at least n=4. So, this covers n=4 to n=7.

1/λ =(1.097 × 10⁻7)(1/4² -1/7²)
λ  = 216.57 ×10⁻⁶ m or 216.57 μm
5 0
2 years ago
Hypothesis: If a fixed amount of gas is heated,
dezoksy [38]

Answer:

If fixed amount of gas is heated then the volume will increase because the heat will cause the molecules of gas to move freely and increase the kinetic energy.

Explanation:

If fixed amount of gas is heated then the volume will increase because the heat will cause the molecules of gas to move freely and increase the kinetic energy.

According to the Charle's law

The volume of given amount of gas is directly proportional to the temperature at constant pressure and number of moles of gas.

Mathematical expression;

V ∝ T

V = kT

V/T = k

if volume is changed from V1 to V2 and temperature change from T1 to T2 then,

V1/T1 = k      V2/T2= k

V1/T1 = V2/T2

6 0
2 years ago
Read 2 more answers
Consider a general reaction A ( aq ) enzyme ⇌ B ( aq ) A(aq)⇌enzymeB(aq) The Δ G ° ′ ΔG°′ of the reaction is − 5.980 kJ ⋅ mol −
Grace [21]

Answer : The value of K_{eq} is, 11.2

The value of \Delta G_{rxn} is -9.04 kJ/mol

Explanation :

The relation between the equilibrium constant and standard Gibbs free energy is:

\Delta G^o=-RT\times \ln K_{eq}

where,

\Delta G^o = standard Gibbs free energy  = -5.980 kJ/mol = -5980 J/mol

R = gas constant = 8.314 J/K.mol

T = temperature = 25^oC=273+25=298K

K_{eq}  = equilibrium constant  = ?

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

\Delta G^o=-RT\times \ln K_{eq}

-5980J/mol=-(8.314J/K.mol)\times (298K)\times \ln K_{eq}

K_{eq}=11.2

Thus, the value of K_{eq} is, 11.2

Now we have to calculate the \Delta G_{rxn}.

The formula used for \Delta G_{rxn} is:

The given reaction is:

A(aq)\rightleftharpoons B(aq)

\Delta G_{rxn}=\Delta G^o+RT\ln Q

\Delta G_{rxn}=\Delta G^o+RT\ln \frac{[B]}{[A]}    ............(1)

where,

\Delta G_{rxn} = Gibbs free energy for the reaction  = ?

\Delta G_^o =  standard Gibbs free energy  = -30.5 kJ/mol

R = gas constant = 8.314\times 10^{-3}kJ/mole.K

T = temperature = 37.0^oC=273+37.0=310K

Q = reaction quotient

[A] = concentration of A = 1.8 M

[B] = concentration of B = 0.55 M

Now put all the given values in the above formula 1, we get:

\Delta G_{rxn}=(-5980J/mol)+[(8.314J/mole.K)\times (310K)\times \ln (\frac{0.55}{1.8})

\Delta G_{rxn}=-9035.75J/mol=-9.04kJ/mol

Therefore, the value of \Delta G_{rxn} is -9.04 kJ/mol

3 0
2 years ago
mastering chem If the experiment below is run for 60 s, 0.16 mol A remain. Which of the following statements is or are true? At
Dvinal [7]

Answer: All of the statements are true.

Explanation:

(a) Considering the system mentioned in the equation:-

The sum of total moles in the flask will always be equal to 1 which leads to confirmation of this statement as for 60 secs= 0.16 mol A and 0.84 mol B

(b) 0<t< 20s,  mole A got reduced from 1 mole to 0.54 moles while at 40s to 60s A got decreased from 0.30 moles to 0.16 moles.

0 to 20s is 0.46 (1 - 0.54 = 0.46)mol whereas,

40 to 60s is 0.14 (0.30-.16 = 0.14) mol

(0.46 > 0.14) mol leading this statement to be true as well.

(c) Average rate from t1 = 40 to t2 = 60 s is given by:

\delta moles/\delta time  = 0.30-0.16/60-40 = 0.007 Mol/s which is true as well

7 0
2 years ago
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