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3 years ago

A sample of gas at 25ºc has a volume of 11 l and exerts a pressure of 660 mm hg. how many moles of gas are in the sample?

1 answer:

5 0

The moles of the gas in the sample is 0.391 moles

calculation
by use of ideal gas equation, that is Pv=nRT
where n is number of moles
P(pressure)= 660 mmhg
R(gas constant) = 62.364 l.mmhg/mol.K
T(temperature)= 25 +273 = 298 k

by making n the subject of the formula

n= Pv/ RT

n is therefore= (660mm hg x11 L)/( 62.364 L.mmhg/mol.k x298 K) = 0.391 moles

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B fossils

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8 0

2 years ago

A sample of nitrogen gas, (N2), occupies 45.0 mL at 27.00∘C and 80.0 kPa. What will be the pressure if the gas is cooled to −73.

maxonik [38]

Answer:

The new pressure is 53.3 kPa

Explanation:

This problem can be solved by this law. when the volume remains constant, pressure changes directly proportional as the Aboslute T° is modified.

T° increase → Pressure increase

T° decrease → Pressure decrease

In this case, temperature was really decreased. So the pressure must be lower.

P₁ / T₁ = P₂ / T₂

80 kPa / 300K = P₂/200K

(80 kPa / 300K) . 200 K = P₂ → 53.3 kPa

6 0

2 years ago

A scientist measures the standard enthalpy change for the following reaction to be -17.2 kJ : Ca(OH)2(aq) 2 HCl(aq)CaCl2(s)

elixir [45]

Answer: $\Delta H^{0}=-173.72$ kJ/mol

Explanation: Enthalpy Change is the amount of energy in a reaction - absorption or release - at a constant pressure. So, Standard Enthalpy of Formation is how much energy is necessary to form a substance.

The standard enthalpy of formation of HCl is calculated as:

$\Delta ^{0}=\Sigma H_{products}-\Sigma H_{reactants}$

$Ca(OH)_{2}_{(aq)}+2HCl_{(aq)}$ → $CaCl_{2}_{(s)}+2H_{2}O_{(l)}$

Standard Enthalpy of formation for the other compounds are:

Calcium Hydroxide: $\Delta H^{0}=$ -1002.82 kJ/mol

Calcium chloride: $\Delta H^{0}=$ -795.8 kJ/mol

Water: $\Delta H^{0}=$ -285.83 kJ/mol

Enthalpy is given per mol, which means we have to multiply by the mols in the balanced equation.

Calculating:

$-17.2=[-795.8+2(285.85)]-[-1002.82+2\Delta H]$

$-17.2=-1367.46+1002.82-2\Delta H$

$2\Delta H=17.2-364.64$

$\Delta H=-173.72$

So, the standard enthalpy of formation of HCl is -173.72 kJ/mol

8 0

2 years ago

One mechanism for the synthesis of ammonia proposes that N₂ and H₂ molecules catalytically dissociate into atoms:N₂ ⇆ 2N(g) log

Pavlova-9 [17]

The artificial fixation of nitrogen (N2) has enormous energy, environmental, and societal impact, the most important of which is the synthesis of ammonia (NH3) for fertilizers that help support nearly half of the world's population.

<h3>Artificial fixation of nitrogen</h3>

a) The equilibrium constant expression is Kp=PCH4 PH2 OP CO×PH 23.

(b) (i) As the pressure increases, the equilibrium will shift to the left so that less number of moles are produced.

(ii) For an exothermic reaction, with the increase in temperature, the equilibrium will shift in the backward direction.

(iii) When a catalyst is used, the equilibrium is not disturbed. The equilibrium is quickly attained

To learn more about equilibrium constant visit the link

brainly.com/question/10038290

#SPJ4

6 0

1 year ago

given the following hypothetical reaction 2E(g)+ F(g)+O(g)_products.if the rate law is rate _K(e)^2(f)^-1,what is the order of t

Yuliya22 [10]

Answer:

See explanation.

Explanation:

Hello there!

In this case, considering the given information, it is not possible to figure out such order of reaction with respect to water as it is not involved in the given chemical reaction:

2E(g)+ F(g)+O(g)_

However, we can say that the order of reaction is 2 with respect to E (power of 2 in the rate law), 1 with respect to F (power of 1 in the rate law) and 0 with respect to O (power of 0 or not present in the rate law).

Regards!

8 0

2 years ago