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3 years ago

A. Explain the difference between an exothermic chemical reaction and an endothermic chemical reaction.

1 answer:

7 0

A. Exo means outside, Endo means inside, and thermic means heat!
B. Enthalpy of reaction= enthalpy of formation of products

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Adding luminol to water creates a physical or chemical change

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Answer: chemical

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Write the isotopic symbol for the following (show your work) a) An isotope of iodine whose atoms have 78 neutrons b) An isotope

morpeh [17]

Answer:

For a: The isotopic representation of iodine is $_{53}^{131}\textrm{I}$

For b: The isotopic representation of cesium is $_{55}^{137}\textrm{Cs}$

For c: The isotopic representation of strontium is $_{38}^{52}\textrm{Sr}$

Explanation:

The isotopic representation of an atom is: $_Z^A\textrm{X}$

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

For a:

We are given:

Number of neutrons = 78

Atomic number of iodine = 53 = Number of protons

Mass number = 53 + 78 = 131

Thus, the isotopic representation of iodine is $_{53}^{131}\textrm{I}$

For b:

We are given:

Number of neutrons = 82

Atomic number of cesium = 55 = Number of protons

Mass number = 55 + 82 = 137

Thus, the isotopic representation of cesium is $_{55}^{137}\textrm{Cs}$

For c:

We are given:

Number of neutrons = 52

Atomic number of strontium = 38 = Number of protons

Mass number = 38 + 52 = 90

Thus, the isotopic representation of strontium is $_{38}^{52}\textrm{Sr}$

3 0

3 years ago

: How much energy is required to heat an iron nail with a mass of 25.5 grams from 65°C until it becomes red hot at 720°C?

Evgen [1.6K]

Q = mct

-Q= energy in Joules

-m = mass in grams

-c= specific heat capacity in J/g degree C

-t = delta temperature in degrees Celsius

So,

Q = m c t

Q = (7 grams)(0.448J/g C)(750 C - 25 C)

Q = 2273.6 J

Your final answer = 2273.6 Joules

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3 years ago

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tresset_1 [31]

Metallic properties head to the left.

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