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3 years ago

If the temperature of 15 grams of water changes from 21C to 24C, how many joules of heat were involved? Show work

Chemistry

1 answer:

goblinko [34]3 years ago

6 0

Answer:

189 Joules

Explanation:

Applying,

Q = cm(t₂-t₁)............. equation 1

Where Q = Heat, c = specific heat capacity of water, m = mass of water, t₁ = Initial Temperature, t₂ = Final temperature.

From the question,

Given: m = 15 grams = 0.015 kg, t₁ = 21 °C, t₂ = 24 °C

Constant: c = 4200J/kg.°C

Substitute these values into equation 1

Q = 0.015×4200×(24-21)

Q = 0.015×4200×3

Q = 189 Joules

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Aluminum chloride can be formed from its elements:

saul85 [17]

<u>Answer:</u> The $\Deltas H^o_{formation}$ for the reaction is -1406.8 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 chemical reaction for the formation reaction of $AlCl_3$ is:

$2Al(s)+3Cl_2(g)\rightarrow 2AlCl_3 (s)$ $\Delta H^o_{formation}=?$

The intermediate balanced chemical reaction are:

(1) $HCl(g)\rightarrow HCl(aq.)$ $\Delta H_1=-74.8kJ$ ( × 6)

(2) $H_2(g)+Cl_2(g)\rightarrow 2HCl(g)$ $\Delta H_2=-185kJ$ ( × 3)

(3) $AlCl_3(aq.)\rightarrow AlCl_3(s)$ $\Delta H_3=+323kJ$ ( × 2)

(4) $2Al(s)+6HCl(aq.)\rightarrow 2AlCl_3(aq.)+3H_2(g)$ $\Delta H_4=-1049kJ$

The expression for enthalpy of formation of $AlCl_3$ is,

$\Delta H^o_{formation}=[6\times \Delta H_1]+[3\times \Delta H_2]+[2\times \Delta H_3]+[1\times \Delta H_4]$

Putting values in above equation, we get:

$\Delta H^o_{formation}=[(-74.8\times 6)+(-185\times 3)+(323\times 2)+(-1049\times 1)]=-1406.8kJ$

Hence, the $\Deltas H^o_{formation}$ for the reaction is -1406.8 kJ.

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One hundred million copper atoms are arranged in a line. Which is a reasonable estimate for the length of this line?

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0.01 x 100 = 1 centimetre

There’s your answer

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Flura [38]

Answer:

Explanation:

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Element A has 15 protons. Determine the number of neutrons in its isotope with mass number 33.

mario62 [17]

33 - 15 = 18
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Can someone help me with this one

jek_recluse [69]

Answer:

Easy my dude let me help you out

A.In

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Also with protons and electrons they equal the same atomic number

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