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Finger [1]
3 years ago
6

When using science to investigate physical phenomena, which characteristic of the event must exist?

Chemistry
1 answer:
Maru [420]3 years ago
5 0
 "Observable" is the one characteristic of event that must exist when <span>using science to investigate physical phenomena. </span>
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What part of an atom is involved in a chemical reaction?
Katyanochek1 [597]

Answer:

The answer is supposed to be "Electron cloud" or "Electon".

5 0
4 years ago
Determine the enthalpy change for the reaction 2C(s) + 2H2O(g) → CH4(g) + CO2(g) using the following:
Sophie [7]

Answer : The enthalpy change for the reaction is, 97.7 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

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

The given main chemical reaction is,

2C(s)+3H_2O(g)\rightarrow CH_4(g)+CO_2(g)    \Delta H=?

The intermediate balanced chemical reaction will be,

(1) C(s)+H_2O(g)\rightarrow CO(g)+H_2(g)     \Delta H_1=131.3kJ

(2) CO(g)+H_2O(g)\rightarrow CO_2(g)+H_2(g)    \Delta H_2=41.2kJ

(3) CH_4(g)+H_2O(g)\rightarrow 2H_2(g)+CO(g)    \Delta H_3=206.1kJ

Now we are multiplying reaction 1 by 2 and reversing reaction 3 and then adding all the equations, we get :

(1) 2C(s)+2H_2O(g)\rightarrow 2CO(g)+2H_2(g)     \Delta H_1=2\times 131.3kJ=262.6kJ

(2) CO(g)+H_2O(g)\rightarrow CO_2(g)+H_2(g)    \Delta H_2=41.2kJ

(3) 2H_2(g)+CO(g)\rightarrow CH_4(g)+H_2O(g)    \Delta H_3=-206.1kJ

The expression for enthalpy of main reaction will be,

\Delta H=\Delta H_1+\Delta H_2+\Delta H_3

\Delta H=(262.6)+(41.2)+(-206.1)

\Delta H=97.7kJ

Therefore, the enthalpy change for the reaction is, 97.7 kJ

3 0
4 years ago
Read 2 more answers
An insulator,
Sedaia [141]
Hey there !

The answer would be C. Is when electrons cannot nice through objects easily.

Any material that keeps energy such as electricity, heat, or cold from easily transferring through is an insulator. Wood, plastic, rubber, and glass are good insulators.

Hope this helps !
8 0
3 years ago
what is the differents between the number of electrons in selenium and the number of electrons in aluminum ?
uysha [10]

Answer:

The number of protons in the nucleus of the atom is equal to the atomic number (Z). The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.

8 0
3 years ago
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Which of the following describes the size of gamma rays?
IRINA_888 [86]
C. Gamma rays have a shorter wavelength than X-rays.
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3 years ago
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