Which is equal to a temperature of 50°F? O 18°C O 46°C O 10°C O 32°C

1. Is the reaction between magnesium and oxygen in the air spontaneous?

Vikki [24]

Answer:

Once ignited, a ribbon of magnesium metal burns freely in air to form solid magnesium oxide in the form of a white powder. The reaction is plainly spontaneous even though ΔS is negative.

4 0

3 years ago

2nh3(g) → n2(g) + 3h2(g) the reaction for the decomposition of ammonia (nh3) can be written as shown. if a student starts with 2

spin [16.1K]

3.85 :) .....................................................................

4 0

3 years ago

Read 2 more answers

When of a certain molecular compound X are dissolved in of benzene , the freezing point of the solution is measured to be . Calc

puteri [66]

The question is incomplete. Here is the complete question.

When 2.10 g of a certain molecular compound X are dissolved in 65.0 g of benzene (C₆H₆), the freezing point of the solution is measured to be 3.5°C. Calculate the molar mass of X. If you need any additional information on benzene, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to 2 significant digits.

Answer: MM = 47.30 g/mol.

Explanation: There is a relationship between freezing point depression and molality. With this last one, is possible to calculate molar mass or molar weight of a compound.

Freezing Point Depression occurs when a solute is added to a solvent: the freezing point of the solvent decreases when a non-volatile solute is incremented.

Molality or molal concentration is a quantity of solute dissolved in a certain mass, in kg, of solvent. Its symbol is m and it's defined as

$m=\frac{moles(solute)}{kg(solvent)}$

Freezing point depression and molal are related as the following:

$\Delta T_{f}=K_{f}.m$

where

$\Delta T_{f}$ is freezing point depression of solution

$K_{f}$ is molal freezing point depression constant

m is molality

Now, to determine molar mass, first, find molality of the mixture:

$\Delta T_{f}=K_{f}.m$

$m=\frac{\Delta T_{f}}{K_{f}}$

For benzene, constant is 5.12°C/molal. Then

$m=\frac{3.5}{5.12}$

m = 0.683 molal

Second, knowing the relationship between molal and moles of solute, determine the last one:

$m=\frac{moles(solute)}{kg(solvent)}$

$mol(solute)=m.kg(solvent)$

mol(solute) = 0.683(0.065)

mol(solute) = 0.044 mol

The definition for Molar mass is the mass in grams of 1 mol of substance:

$n(moles)=\frac{m(g)}{MM(g/mol)}$

$MM=\frac{m}{n}$

In the mixture, there are 0.044 moles of X, so its molecular mass is

$MM=\frac{2.1}{0.044}$

MM = 47.30 g/mol

The molecular compound X has molecular mass of 47.30 g/mol.

7 0

3 years ago

HELP!!! What is the product of the top reaction?

Fofino [41]

Meso−2,3−butanediol is the product of the top reaction

5 0

2 years ago

A 250.0 mL sample of aqueous solution contains an unknown amount of dissolved NaBr. Excess aqueous Pb(NO3)2is then added to this

Scrat [10]

Answer:

A. 0.0655 mol/L.

B. PbBr2.

C. Pb2+(aq) + Br- --> PbBr2(s).

Explanation:

Balanced equation of the reaction:

Pb(NO3)2(aq) + 2NaBr(aq) --> PbBr2(s) + 2NaNO3(aq)

A.

Number of moles

PbBr2

Molar mass = 207 + (80*2)

= 367 g/mol.

Moles = mass/molar mass

= 3.006/367

= 0.00819 mol.

Since 2 moles of NaBr reacted to form 1 mole of PbBr2. Therefore, moles of NaBr = 2*0.00819

= 0.01638 moles of NaBr.

Since, the ionic equation is

NaBr(aq) --> Na+(aq) + Br-(aq)

Since 1 moles of NaBr dissociation in solution to give 1 mole of Br-

Therefore, molar concentration of Br-

= 0.0164/0.25 L

= 0.0655 mol/L.

B.

PbBr2

C.

Pb(NO3)2(aq)--> Pb2+(aq) + 2No3^2-(aq)

2NaBr(aq) --> 2Na+(aq) + 2Br-(aq)

Net ionic equation:

Pb2+(aq) + 2Br- --> PbBr2(s)

8 0

3 years ago