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STatiana [176]
2 years ago
10

Large telescopes have revealed information about the motions of stars. They helped scientists realize that most stars and galaxi

es are accelerating away from one another. This led scientists to begin to develop the big bang theory. This new theory explained that the universe began as an enormous explosion outward from a single point. The work described in the passage is part of which process used in developing scientific theories? O A. Using observations to spark an idea O B. Using data to develop new technology C. Using imagination to modify existing technology D. Using new technology to modify an existing theory. PLEASE I NEED HELP!!!!
​
Chemistry
1 answer:
fiasKO [112]2 years ago
5 0

Answer:b

Explanation:sorry if I’m wrong

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Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol SrO (s) + CO₂ (g) → SrCO₃ (s) ∆H° = -234 kJ/mol CO₂ (g) → C(
kkurt [141]

<u>Answer:</u> The \Delta H^o_{rxn} for the reaction is 72 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

2SrCO_3(s)\rightarrow 2Sr(s)+2C(s)+3O_2(g)      \Delta H^o_{rxn}=?

The intermediate balanced chemical reaction are:

(1) 2Sr(s)+O_2(g)\rightarrow 2SrO(s)    \Delta H_1=-1184kJ

(2) SrO(s)+CO_2(g)\rightarrow SrCO_3(s)     \Delta H_2=-234kJ      ( × 2)

(3) CO_2(g)\rightarrow C(s)+O_2(g)     \Delta H_3=394kJ    ( × 2)

The expression for enthalpy of the reaction follows:

\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[2\times (-\Delta H_2)]+[2\times (\Delta H_3)]

Putting values in above equation, we get:

\Delta H^o_{rxn}=[(1\times (-1184))+(2\times -(-234))+(2\times (394))]=72kJ

Hence, the \Delta H^o_{rxn} for the reaction is 72 kJ.

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Answer:

The answer is A, I think.

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Can a molecule have polar bonds, but still be a no polar molecule?
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<em><u>A molecule </u></em><em><u>can </u></em><em><u>possess polar bonds and still be nonpolar.</u></em>

I hope this helped. Have a nice day, make sure to take care of yourself. You're loved <3

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You’ve been waiting for the bus and your hands become cold. When you get onto the bus and sit down, you put your hands under you
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Explanation:

The <u>First Law of Thermodynamics</u> states that energy cannot be created or destroyed in an isolated system. In other words, energy can be converted from one form into another, but it cannot be created nor destroyed.

<u>Conduction</u> is the transfer of energy from one molecule to another by direct contact. This transfer occurs when molecules hit against each other, which can take place in solids, liquids, and gases.

When you put your cold hands under your legs to warm your hands up, the heat energy from your legs is being transferred to your hands through conduction. However, since energy cannot be created, there is no extra heat energy that can instantaneously replace the heat created by your legs.

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