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dedylja [7]
3 years ago
7

How many moles of helium gas are contained in a 4.0-L flask at STP?

Chemistry
2 answers:
ExtremeBDS [4]3 years ago
7 0

Answer:

0.1784 moles of helium gas are contained in a 4.0-L flask at STP.

Explanation:

At STP. temperature of the helium gas = T = 273.15 K

At STP, pressure of the helium  gas = P = 1 atm

Volume of the helium  gas at STP  = V = 4.0 L

Moles of the helium  gas = n

Using an ideal gas equation :

PV=nRT

n=\frac{PV}{RT}=\frac{1 atm\times 4.0 L}{0.0821 atm L/mol K\times 273.15 K}

n = 0.1784 mol

0.1784 moles of helium gas are contained in a 4.0-L flask at STP.

mel-nik [20]3 years ago
4 0
1.0 mole of gas at STP occupies 22.4 Litres.
4/0L / 22.4 L/mole = 0.179 moles He.
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In the reaction C + O2 → CO2, 18 g of carbon react with oxygen to produce 72 g of carbon dioxide. What mass of oxygen would be n
melamori03 [73]

Answer:

54 g

Explanation:

Given data:

Mass of carbon = 18 g

Mass of CO₂ = 72 g

Mass of oxygen needed = ?

Solution:

Chemical reaction:

C + O₂     →       CO₂

according to law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

This law was given by French chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

In given photosynthesis reaction:

6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂

there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.

In a similar way,

C   +    O₂     →       CO₂

18 g +   X      = 72

X = 72 -18

X = 54 g

Thus, 54 g of O₂ are required.

3 0
2 years ago
Read 2 more answers
Give the ground-state electron configuration for silicon (SiSi) using noble-gas shorthand. Express your answer in condensed form
nydimaria [60]

Answer:

[Ne] 3s² 3p²

Explanation:

Silicon atoms have 14 electrons. The ground state electron configuration of ground state gaseous neutral silicon is 1s²2s²2p⁶3s²3p².

Using noble gas shorthand, the electronic configuration is reduced to;

[Ne] 3s² 3p². Ne s the nearest noble gas to silicon, Ne contains 8 electrons, this means there's still 4 more electrons to fill. The s orrbital can only hold 2, hence the reaing two is transferred to the p orbital.

5 0
3 years ago
When equal volumes of 0.5 M HCl and 0.5 M Ca(OH)2 are mixed, the resulting solution is
Mademuasel [1]

The concentration of mixed solution = 0.5 M

<h3> Further explanation </h3>

Given

0.5 M HCl

0.5 M Ca(OH)₂

Required

The concentration

Solution

Molarity from 2 solutions :

Vm Mm = V₁. M₁ + V₂. M₂  

m = mixed solution

V = volume

M = molarity

V = mixed volume  

1 = solution 1

2 = solution 2

Vm = V₁+V₂

Equal volumes⇒V₁=V₂, and Vm = 2V, then equation becomes :

2V.Mm = V(M₁+M₂)

2V.Mm = V(0.5+0.5)

Mm=0.5 M

8 0
2 years ago
The thermochemical equation for the reaction of carbon dioxide with sulfur dioxide is shown below. How can the reaction be descr
prisoha [69]

Answer: d. has high activation energy

Activation energy is the energy that a system requires to start a certain process. Also, it <u>is the minimum energy necessary for a given chemical reaction to occur</u>. For a reaction to occur between two molecules, they must collide in the correct orientation and have a minimum amount of energy equal to the activation energy.

As the molecules approach, their electron clouds repel, so energy is required for the collision to occur and therefore the reaction. The activation energy comes from the heat of the system, that is, the translational, vibrational energy, etc. of each molecule. However, if this energy is not enough, the reaction will not be spontaneous.

<u>A reaction between two molecules can be favored by supplying energy to the system.</u> In the case raised in the question, <u>energy equal to 1104 kJ is provided to the system to favor the next reaction </u>

CO2 (g) + 2SO2 (g) → CS2 (g) + 3O2 (g)

<u>Since the energy equal to 1104 kJ is included in the reactants, it can be deduced that it is the energy that is provided to the system for the reaction to occur. </u>However, from the value of this energy it can not be said whether the system is endothermic or exothermic since it is a kinetic variable and the variables of this type do not allow predicting the thermodynamic behavior of a system.

Furthermore, it can be seen that the value of this energy is considerably high, therefore the reaction described has a high activation energy.

3 0
2 years ago
WILL GIVE OUT BRAINLY
Margarita [4]

Answer:

3. An oxygen atom with 8 electrons, 8 protons, and 9 neutrons .

Explanation:

if an atom contains equal numbers of protons and electrons, the atom is described as being neutral.

4 0
2 years ago
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