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3 years ago

I NEED HELP PLEASE !!!!!

Chemistry

2 answers:

Andrei [34K]3 years ago

4 0

Second choice : technology has replaced humans needs

Jobisdone [24]3 years ago

3 0

Answer: My opinion is the second one because a lot of humans uses technology and technilogy replaces a lot of stuff.

Explanation:

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A scientist measures the standard enthalpy change for the following reaction to be -17.2 kJ : Ca(OH)2(aq) 2 HCl(aq)CaCl2(s)

elixir [45]

Answer: $\Delta H^{0}=-173.72$ kJ/mol

Explanation: Enthalpy Change is the amount of energy in a reaction - absorption or release - at a constant pressure. So, Standard Enthalpy of Formation is how much energy is necessary to form a substance.

The standard enthalpy of formation of HCl is calculated as:

$\Delta ^{0}=\Sigma H_{products}-\Sigma H_{reactants}$

$Ca(OH)_{2}_{(aq)}+2HCl_{(aq)}$ → $CaCl_{2}_{(s)}+2H_{2}O_{(l)}$

Standard Enthalpy of formation for the other compounds are:

Calcium Hydroxide: $\Delta H^{0}=$ -1002.82 kJ/mol

Calcium chloride: $\Delta H^{0}=$ -795.8 kJ/mol

Water: $\Delta H^{0}=$ -285.83 kJ/mol

Enthalpy is given per mol, which means we have to multiply by the mols in the balanced equation.

Calculating:

$-17.2=[-795.8+2(285.85)]-[-1002.82+2\Delta H]$

$-17.2=-1367.46+1002.82-2\Delta H$

$2\Delta H=17.2-364.64$

$\Delta H=-173.72$

So, the standard enthalpy of formation of HCl is -173.72 kJ/mol

8 0

3 years ago

What are the reactants in the reaction? What are their properties? Perform a quick Internet search, if needed.

Helen [10]

The reactants in this reaction are sodium and chlorine. Sodium is a soft, silvery-white metal that is highly reactive. Chlorine is a poisonous greenish-yellow gas that has an odor and combines readily with other elements.

This might be the exact question so you might wanna rephrase it but good luck! :)))

7 0

3 years ago

If energy cannot be created, where did the types of energy you observed when the tortilla chip burned come from?

anzhelika [568]

The fire that burned the chip is thermal energy.

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3 years ago

What are the three heredity rules ?

Nataly [62]

The Law of Dominance. ...
The Law of Segregation. ...
The Law of Independent Assortment.

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