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3 years ago

20 mL of 80°C water is mixed with 20 mL of 0°C water in a perfect calorimeter. What is the final temperature?

1 answer:

8 0

To calculate for the final temperature, we need to remember that the heat rejected should be equal to the absorbed by the other system. We calculate as follows:

Q1 = Q2
(mCΔT)1 = (mCΔT)2

We can cancel m assuming the two systems are equal in mass. Also, we cancel C since they are the same system. This leaves us,

(ΔT)1 = (ΔT)2
(T - 80) = (0 - T)
T = 40°C

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Consider the half reaction below.

Radda [10]

Answer: the second option: <span>Iron is being oxidized
</span>

Explanation:

1) Oxidation is the increase of the oxidation state (number) due to the loss of electrons.

2) In the given reaction, you can see that in the left side the atom is Fe.

When an element (atom) is not combined (or combined with it self) its oxidation state is 0.

3) In the right side of the given equation you that iron is now in form of cation with charge 2+: Fe²⁺.

That means that the new oxidation state of the element is 2+.

4) This change in the oxidation state, of course, is accompanied by the loss of the two electrons: 2e⁻.

5) Conclusion: the iron has oxidized by losing two electrons and increasing its oxidation state from 0 to 2+.
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7 0

3 years ago

PH CHEM, PLEASE HELP QUICK! NO LINKS/VIRUSES PLEASE!

Contact [7]

Answer:

The pH of the solution is 11.48.

Explanation:

The reaction between NaOH and HCl is:

NaOH + HCl → H₂O + NaCl

From the reaction of 3.60x10⁻³ moles of NaOH and 5.95x10⁻⁴ moles of HCl we have that all the HCl will react and some of NaOH will be leftover:

$n_{NaOH}} = n_{i_{NaOH}} - n_{HCl} = 3.60 \cdot 10^{-3} moles - 5.95 \cdot 10^{-4} moles = 3.01 \cdot 10^{-3} moles$

Now, we need to find the concentration of the OH⁻ ions.

$[OH^{-}] = \frac{n_{NaOH}}{V}$

Where V is the volume of the solution = 1.00 L

$[OH^{-}] = \frac{n_{NaOH}}{V} = \frac{3.01 \cdot 10^{-3} moles}{1.00 L} = 3.01 \cdot 10^{-3} mol/L$

Finally, we can calculate the pH of the solution as follows:

$pOH = -log([OH^{-}]) = -log(3.01 \cdot 10^{-3}) = 2.52$

$pH + pOH = 14$

$pH = 14 - pOH = 14 - 2.52 = 11.48$

Therefore, the pH of the solution is 11.48.

I hope it helps you!

3 0

2 years ago

Easy way to remember the difference between ionic and covalent bonds?

patriot [66]

Answer:

ionic bonding occurs between ions and covalent bonding occurs when atoms have electrons in common (they share).

5 0

1 year ago

What is a molar solution?

mina [271]

Answer:

Molar concentration is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution. In chemistry, the most commonly used unit for molarity is the number of moles per liter, having the unit symbol mol/L or mol/dm³ in SI unit.

8 0

2 years ago

How many grams are in 4.56 moles of Mg(OH)2

GalinKa [24]

D. divide 4.56 by molar mass of mg(OH)2

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3 years ago