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3 years ago

Which statement about the energy of a phase change is true?

2 answers:

4 0

Since with melting the solid absorbs the heat of the environment in order to get the energy needed to phase change from solid to liquid, it means that melting is endothermic.

Evidence of this is that if you have a hot tea, and you put ice cubes in it along with a thermometer, as the ice melts you will realize that the temperature of the tea would decrease thus insinuating that heat was removed from the tea (absorbed by the ice to melt).

Answer: OPTION B

strojnjashka [21]3 years ago

3 0

Answer:

Explanation:

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2.What is the chemical formula<br> for ammonium nitrite

jeyben [28]

Answer:

NH4NO3

Explanation:

I hope this helps you:)

5 0

3 years ago

12) A 17.92 g sample of copper was submerged in water, and the volume reading rose by 2.00 mL. What is the density of the copper

emmasim [6.3K]

Hey there!:

Mass = 17.92 g

Volume = 2.00 mL

Density = ??

Therefore:

D = m / V

D = 17.92 / 2.00

D = 8.96 g/mL

Hope this helps!

3 0

3 years ago

Which element has the HIGHEST ionization energy? (Hint: it's hardest to remove an electron from this element)

Bumek [7]

Answer:

Argon

Explanation:

5 0

3 years ago

Read 2 more answers

A weak monoprotic acid is titrated with 0.100 MNaOH. It requires 50.0 mL of the NaOH solution to reach the equivalence point. Af

larisa86 [58]

Explanation:

The given reaction is as follows.

$HA(aq) + NaOH (aq) \rightleftharpoons NaA(aq) + H_{2}O(l)$

Hence, number of moles of NaOH are as follows.

n = $0.05 L \times 0.1 M$

= 0.005 mol

After the addition of 25 ml of base, the pH of a solution is 3.62. Hence, moles of NaOH is 25 ml base are as follows.

n = $0.025 L \times 0.1 M$

= 0.0025 mol

According to ICE table,

$HA(aq) + NaOH (aq) \rightleftharpoons NaA(aq) + H_{2}O(l)$

Initial: 0.005 mol 0.0025 mol 0 0

Change: -0.0025 mol -0.0025 mol +0.0025 mol

Equibm: 0.0025 mol 0 0.0025 mol

Hence, concentrations of HA and NaA are calculated as follows.

[HA] = $\frac{0.0025 mol}{V}$

[NaA] = $\frac{0.0025 mol}{V}$

$[A^{-}] = [NaA] = \frac{0.0025 mol}{V}$

Now, we will calculate the $pK_{a}$ value as follows.

pH = $pK_{a} + log \frac{A^{-}}{HA}$

$pK_{a} = pH - log \frac{[A^{-}]}{[HA]}$

= $3.42 - log \frac{\frac{0.0025 mol}{V}}{\frac{0.0025}{V}}$

= 3.42

Thus, we can conclude that $pK_{a}$ of the weak acid is 3.42.

8 0

3 years ago

820 g Li2SO4 is dissolved into 2500 mL of solution. What is the molar concentration?

Andreas93 [3]

Molarity is defined as the moles of solute per liter of solution. $M=\frac{n}{V}$ . Where M is molarity, n is the number of moles and V is the volume. First we must find the molar mass of $Li_2SO_4$ which is 109.98 g/mol

$Li_2SO_4= 2 \times Li_{Ar} + S_{Ar} + 4 \times O_{Ar}\\= (2 \times 6.941 + 32.1 + 4 \times 16.0) = 109.98 g/mol$

$820\ g\ Li_2SO_4 \times \frac{mol}{109.98\ g}= 7.46\ mol\ Li_2SO4$

Then we find the molarity using above equation

$M= \frac{n}{V} = \frac{7.46 mol}{2500ml} \times\frac{1000ml}{L} = 2.98\ M$

6 0

3 years ago