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3 years ago

Question 65 pts

Chemistry

1 answer:

romanna [79]3 years ago

3 0

Answer:

It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed

Explanation:

A reaction may be endothermic or exothermic. In an endothermic reaction, energy is absorbed by the process while in an exothermic process energy is given out by the process.

Recall that the enthalpy change of a reaction = enthalpy of products - enthalpy of reactants

Hence, where the energy required to break bonds in the reactants is less than the energy released when the products are formed, the reaction is endothermic.

For an endothermic reaction, the enthalpy change of the reaction is positive.

In this case, enthalpy of reaction = 920 - (-750) = 1670 kJ/mol

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Convert mass to moles for both reactants. (round to 2 significant figures.)

Maslowich

Answer:

Explanation:

Given parameters:

Mass of CuCl₂ = 2.50g

Mass of Al = 0.50g

Unknown:

Number of moles of CuCl₂ and Al = ?

Solution:

To solve this problem, we must understand that the number of moles is a fundamental property used in stoichiometry calculations.

Number of moles = $\frac{mass}{molar mass}$

Molar mass of CuCl₂ = 63.6 + 2(35.5) = 134.5g/mole

Molar mass of Al = 26.98g/mole

Number of moles of CuCl₂ = $\frac{2.5}{134.5}$ = 0.019moles

Number of moles of Al = $\frac{0.5}{26.98}$ = 0.019moles

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4 years ago

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Which of the following is a direct result of global warming that is causing endangerment of polar bears?

frez [133]

increased warmth causing glaciers to melt

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3 years ago

Green plants absorbs sunlight to power photosynthesis, the chemical synthesis of food from water and carbon dioxide. The compoun

Serggg [28]

Answer: The frequency of this light is $6.62\times 10^{14}s^{-1}$

Explanation:

To calculate the wavelength of light, we use the equation:

$\lambda=\frac{c}{\nu}$

where,

$\lambda$ = wavelength of the light = $453nm=453\times 10^{-9}m$

c = speed of light = $3.0\times 10^8m/s$

$\nu$ = frequency of light = ?

$\nu=\frac{3.0\times 10^8m/s}{453\times 10^{-9}m}=6.62\times 10^{14}s^{-1}$

The frequency of this light is $6.62\times 10^{14}s^{-1}$

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3 years ago

Using the systematic approach for equilibrium problems, calculate the pH of 0.05 M HOCl. Ka= 3.0*10-8 Group of answer choices 3.

SVEN [57.7K]

Answer:

The pH is equal to 4.41

Explanation:

Since HClO is a weak acid, its dissociation in aqueous medium is:

HClO ⇄ ClO- + H+

start: 0.05 0 0

change -x +x +x

balance 0.05-x x x

As it is a weak acid it dissociates very little, in its ClO- and H + ions, so the change is negative, where x is a degree of dissociation.

the acidity constant when equilibrium is reached is equal to:

$Ka=\frac{[ClO-]*[H+]}{[HClO]}=\frac{x*x}{0.05-x}=3x10^{-8}$

The 0.05-x fraction can be approximated to 0.05, because the ionized fraction (x) is very small, therefore we have:

$3x10^{-8}=\frac{x^{2} }{0.05}$

clearing the x and calculating its value we have:

$x=3.87x10^{-5}=[H+]=[ClO-]$

the pH can be calculated by:

$pH=-log[H+]=-log[3.87x10^{-5}]=4.41$

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4 years ago

What is the molarity of a solution prepared by dissolving 2.5 grams of LiNO3 in sufficient water to make 60.0 mL of solution?

Murrr4er [49]

Answer: hope this helps

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2M NaCl solution requires 2.0 x 58.44 g of NaCl = 116.88g.

Explanation:

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4 years ago

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