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3 years ago

Why is refraction so important in eyeglasses.

1 answer:

7 0

It helps our eyes to see better. For example: If you can't read a book because you see that is blurry, you might need glasses to see it much clearer

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Determine the acid dissociation constant for a 0.0250 M weak acid solution that has a pH of 2.37 . The equilibrium equation of i

Oksanka [162]

Answer:

For part (a): pHsol=2.22

Explanation:

I will show you how to solve part (a), so that you can use this example to solve part (b) on your own.

So, you're dealing with formic acid, HCOOH, a weak acid that does not dissociate completely in aqueous solution. This means that an equilibrium will be established between the unionized and ionized forms of the acid.

You can use an ICE table and the initial concentration ofthe acid to determine the concentrations of the conjugate base and of the hydronium ions tha are produced when the acid ionizes

HCOOH(aq]+H2O(l]⇌ HCOO−(aq] + H3O+(aq]

I 0.20 0 0

C (−x) (+x) (+x)

E (0.20−x) x x

You need to use the acid's pKa to determine its acid dissociation constant, Ka, which is equal to

3 0

2 years ago

What is the molarity of a solution that contains 0.202 mol KCl in 7.98 L solution?

mr Goodwill [35]

Explanation:

molarity = no. of moles of solute/solution in litres

molarity =0.202/7.98

=0.025 M

8 0

3 years ago

The Andes Mountains are found along the western coast of South America. Which kind of plate boundary is responsible for this mou

lozanna [386]

The Nazca plate is converging with the South American plate.

Explanation:

The Andes Mountains are formed as a result of the convergent of the Nazca plate and the South American plate.

This mountain range typifies the geology and geography of the South American continent.

Along this convergent margin, one plate subducts beneath the other.
The oceanic plate due to its density goes into the mantle.
The causes the continent riding to obduct and be forced.
With rising magmatic bodies beneath, the continent further pushes up to form the Andes ranges.

Learn more:

Lithosphere brainly.com/question/9582362

#learnwithBrainly

3 0

3 years ago

Calculate the enthalpy of the reaction

harkovskaia [24]

Answer : The enthalpy of the reaction is, -2552 kJ/mole

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 enthalpy of reaction is,

$4B(s)+3O_2(g)\rightarrow 2B_2O_3(s)$ $\Delta H=?$

The intermediate balanced chemical reactions are:

(1) $B_2O_3(s)+3H_2O(g)\rightarrow 3O_2(g)+B_2H_6(g)$ $\Delta H_A=+2035kJ$

(2) $2B(s)+3H_2(g)\rightarrow B_2H_6(g)$ $\Delta H_B=+36kJ$

(3) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l)$ $\Delta H_C=-285kJ$

(4) $H_2O(l)\rightarrow H_2O(g)$ $\Delta H_D=+44kJ$

Now we have to revere the reactions 1 and multiple by 2, revere the reactions 3, 4 and multiple by 2 and multiply the reaction 2 by 2 and then adding all the equations, we get :

(when we are reversing the reaction then the sign of the enthalpy change will be change.)

The expression for enthalpy of the reaction will be,

$\Delta H=-2\times \Delta H_A+2\times \Delta H_B-6\times \Delta H_C-6\times \Delta H_D$

$\Delta H=-2(+2035kJ)+2(+36kJ)-6(-285kJ)-6(+44)$

$\Delta H=-2552kJ$

Therefore, the enthalpy of the reaction is, -2552 kJ/mole

4 0

3 years ago

How many molecules are in one mole of a compound?

valentina_108 [34]

Answer:6.022 x 10^23 molecules

Explanation: Since one mole of any chemical compound always contains 6.022 x 10^23 molecules, you can calculate the number of molecules of any substance if you know its mass and its chemical formula.

3 0

3 years ago