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3 years ago

What the significance of “Er” in the diagram

Chemistry

2 answers:

Galina-37 [17]3 years ago

8 0

Answer:

The answer is D

Explanation:

Vlada [557]3 years ago

3 0

Answer:

Explanation:

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What is the boiling point of a solution made by adding 6.69 g of magnesium chloride to 250.0 g of water?. Use the formula of the

olya-2409 [2.1K]

Answer:

100.432ºC

Explanation:

Ebullioscopy is the elevation of the boiling point of a solvent that has a solute nonvolatile dissolved. The change in the temperature may be calculated by Raoult's law:

ΔT = Kb.W.i

Where ΔT is the temperature change, Kb is the ebullioscopy constant, W is the molality and i is the Van't Hoff factor, which determinates the particles that affect the proper.

The molality is:

W = m1/(M1xm2)

Where m1 is the solute mass (in g), M1 is the molar mass of the solute, and m2 is the mass of the solvent (in kg).

The Van't Hoff factor is the number of final particles divided by the number of initial particles. Magnesium is from froup 2, so it forms the cation Mg⁺², and chlorine ins from group 7 and forms the anion Cl⁻, the salt is MgCl₂ and dissociates:

MgCl₂ → Mg⁺²(aq) + 2Cl⁻(aq)

So, it has 1 particle in initial, and 3 in final (1 Mg⁺² and 2 Cl⁻). So:

i = 3/1 = 3.

The molar mass of MgCl₂ is: 24.3 + 2x35.5 = 95.3 g/mol, m1 = 6.69g, m2 = 0.250 kg, so:

W = 6.69/(95.3x0.250)

W = 0.281 m

Then:

ΔT = 0.512x0.281x3

ΔT = 0.432ºC

The normal boling point of water is 100ºC, so

T - 100 = 0.432

T = 100.432ºC

6 0

3 years ago

Help it’s about Binary compounds and transition metals

Musya8 [376]

Answer:

Cr 6+ & SO4 2-

Explanation:

Sulfate is a polyatomic ion that has a charge of 2-. There are three of them in the chemical formula so it equates to a 6- total charge. Thus, chromium must have a 6+ charge to give the compound a neutral charge.

8 0

3 years ago

What is the pH of a solution that has a [H+] = 0.010 mol/L?

Serjik [45]

Answer:

pH = 2

A 0.010 M solution of hydrochloric acid, HCl, has a molarity of 0.010 M. This means that [H+] = 1 x 10-2 M. The pH of this aqueous solution of H+ ions is pH = 2

hope this helps :3

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5 0

3 years ago

Why water is able to stick to the side of a glass

Snezhnost [94]

Answer:

Water uses adhesive forces that allow it to stick to certain surfaces such as glass.

Explanation:

When the angle between vertical direction and the glass wall is small, surface tension is stronger and the component of gravity perpendicular to the glass wall is small. The result of this causes water to stick to the side of a glass.

Hope this helps!

3 0

3 years ago

Read 2 more answers

Dinitrogen tetroxide and hydrazine (N2H4) undergo a redox reaction in which nitrogen and water are formed as products. What mass

pantera1 [17]

Answer:

The mass of nitrogen molecule $N_2$ = 45.65 g

Explanation:

The equation for the redox reaction can be represented as follows:

$\mathtt{2N_2H_4 +N_2O_4 \ \to \ 3N_2 + 4H_2O}$

We know that:

numbers of moles = mass/molar mass

For $\mathtt{N_2O_4}$ :

number of moles = 50g/92 g/mol

number of moles = 0.5435 mol

For $\mathtt{N_2H_4}$ :

number of moles = 45 g/ 32 g/mol

number of moles = 1.40625 mol

From the above equation;

number of moles of $\mathtt{N_2O_4}$ needed = 1/2 moles of $\mathtt{N_2H_4}$ = 1/2 × 1.40625 mol

= 0.703125 mol

The amount of $\mathtt{N_2O_4}$ present = 0.5435 moles which is less than the needed. As such $\mathtt{N_2O_4}$ is the limiting reagent

The number of moles of nitrogen molecule $N_2$ produced = 3 × ( $\mathtt{N_2O_4}$ )

= 3 × 0.5435

= 1.6305 mol

The mass of nitrogen molecule $N_2$ = number of moles of $N_2$ × molar mass of $N_2$

The mass of nitrogen molecule $N_2$ = 1.6305 mol × 28 g/mol

The mass of nitrogen molecule $N_2$ = 45.654 g

The mass of nitrogen molecule $N_2$ = 45.65 g

7 0

3 years ago