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Andrej [43]
3 years ago
15

X(g)+4Y(g)→2Z(g), ΔH∘=−75.0 kJ Before the reaction, the volume of the gaseous mixture was 5.00 L. After the reaction, the volume

was 2.00 L. Calculate the value of the total energy change, ΔE, in kilojoules.
Chemistry
1 answer:
vlabodo [156]3 years ago
7 0

Isobaric transition, first law: <span>H=ΔU+w</span> for a gas expansion: <span>w=<span>P<span>ext</span></span>∗ΔV</span> to convert to joules, you need the gas constants. R = 0.08206 L atm/mol*K, R=8.314 J/mol*K <span>w=<span>P<span>ext</span></span>∗ΔV∗<span><span>8.314 J/mol∗K</span><span>0.08206 L atm/mol∗K</span></span></span> <span>ΔU=ΔH−[<span>P<span>ext</span></span>∗ΔV∗<span><span>8.314 J/mol∗K</span><span>0.08206 L atm/mol∗K</span></span>]</span> <span>ΔU=−75000 J−[(43.0atm)∗(2−5)L∗<span><span>8.314 J</span><span>0.08206 L atm</span></span>]</span> Then you need to convert to kJ. by the way U=E, internal energy.
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I don’t understand the equations
inna [77]
So the equation is balanced, meaning they have the smallest amounts of each element in the reactants to create the products.

So, 2 moles of H2S (the coefficient) contributes to 2 moles Ag2S, which is why the ratio is 2:2.

I hope that made sense.
6 0
3 years ago
What mass of CO was used up in the reaction with an excess of oxygen gas if 24.7g of carbon dioxide is formed? 2 CO + O2 &gt; 2
Zolol [24]
Balance Chemical Equation,
                                      2 CO  +  O₂   →   2CO₂
Acc. to this reaction,
88 g (2 mole) of CO₂ was produced when  =  56 g (2 mole)of CO was reacted
So, 
24.7 g of CO₂ will be produced by reacting =  X g of CO

Solving for X,
                                    X  =  (56 g × 24.7 g) ÷ 88 g

                                    X  =  2.26 g ÷ 88 g

                                    X  =  0.0257 g of CO

Result:           
            0.0257 g of CO is required to be reacted with excess of O₂ to produce 24.7 g of CO₂.
7 0
3 years ago
Which statement best describes a physical change?
Pepsi [2]

Answer:

The answer is c

7 0
3 years ago
What are the observable indicators that can be evidence a chemical change might have occurred?
kozerog [31]

solution:

The four observations that indicate a chemical change are:  

1) Precipitate is formed  

2) Odour  

3) Heat is emitted ( change in temperature)  

4)Formation of a Gas

Changes of state may of course be merely physical—as for example when liquid water is boiled to form a vapor. (These and other examples of physical changes resulting from temperature changes are discussed in the essays on Properties of Matter; Temperature and Heat.) The vapor produced by boiling water, as noted above, is still water; on the other hand, when liquid water is turned into the elemental gases hydrogen and oxygen, a more profound change has occurred.  

Likewise the addition of liquid potassium chromate (K2CrO4) to a solution of barium nitrate (Ba[NO3]2 forms solid barium chromate (BaCrO4). In the reaction described, a solution is also formed, but the fact remains that the mixture of two solids has resulted in the formation of a solid in a different solution. Again, this is a far more complex phenomenon than the mere freezing of water to form ice: here the fundamental properties of the materials involved have changed.  

The physical change of water to ice or steam, of course, involves changes in temperature; likewise, chemical changes are often accompanied by changes in temperature, the crucial difference being that these changes are the result of alterations in the chemical properties of the substances involved. Such is the case, for instance, when wood burns in the presence of oxygen: once wood is turned to ash, it has become an entirely different mixture than it was before. Obviously, the ashes cannot be simply frozen to turn them back into wood again. This is an example of an irreversible chemical reaction.  

Chemical reactions may also involve changes in color. In specific proportions and under the right conditions, carbon—which is black—can be combined with colorless hydrogen and oxygen to produce white sugar. This suggests another kind of change: a change in taste. (Of course, not every product of a chemical reaction should be tasted—some of the compounds produced may be toxic, or at the very least, extremely unpleasant to the taste buds.) Smell, too, can change. Sulfur is odorless in its elemental form, but when combined with hydrogen to form hydrogen sulfide (H2S), it becomes an evil-smelling, highly toxic gas.  


5 0
3 years ago
7.) A syringe initially holds a sample of gas with a volume of 285 mL at 355 K and 1.88 atm. To
marysya [2.9K]

Answer:

T₂ = 721 k

Explanation:

Given data:

Initial volume = 285 mL

Initial pressure = 1.88 atm

Initial temperature = 355 K

Final temperature = ?

Final volume = 435 mL

Final pressure = 2.50 atm

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

P₁V₁/T₁ = P₂V₂/T₂  

T₂  =  P₂V₂ T₁  / P₁V₁

T₂ = 2.50 atm × 435 mL × 355 K / 1.88 atm × 285 mL  

T₂ = 386062.5 atm. mL. K /535.8 atm. mL

T₂ = 721 k

5 0
3 years ago
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