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MaRussiya [10]
3 years ago
6

A solution of phosphoric acid was made by dissolving 10.0 g of H3PO4 in 100.0 mL of water. The resulting volume was 113 mL. Calc

ulate the density, mole fraction, molarity, and molality of the solution. Assume water has a density of 1.00 g/cm3.
Chemistry
1 answer:
rodikova [14]3 years ago
6 0

Explanation:

Mass of solute = 10.0 g

mass of solvent(water) = m

Volume of solvent( water) = v = 100.0 mL

Density of water= d = 1 g/cm^3=1 g/mL

1 mL= 1 cm^3

m=d\times v=1.0 g/mL\times 100.0 = 100.0 g

Mass of solution(M) = Mass of solute + mass of solvent

M = 10.0 g + 100.0 g = 110.0 g

Volume of the solution = V = 113 mL

Density of the solution = D

D=\frac{M}{V}=\frac{110.0 g}{113 mL}=0.9734 g/mL

The density of the solution is 0.9734 g/ml.

Moles of phosphoric acid = n_1=\frac{10.0 g}{98 g/mol}=0.1020 mol

Moles of water  = n_2=\frac{100.0 g}{18g/mol}=5.556 mol

Mole fraction of phosphoric acid =\chi_1

\chi_1=\frac{n_1}{n_1+n_2}=\frac{0.1020 mol}{0.1020 mol+5.556 mol}

\chi_1=0.01803

Mole fraction of water =\chi_2

\chi_2=\frac{n_2}{n_1+n_2}=\frac{5.556 mol}{0.1020 mol+5.556 mol}

\chi_2=0.9820

[Molarity]=\frac{\text{Moles of solute}}{\text{Volume of solution(L)}}

Moles of  phosphoric acid = 0.1020 mol

Volume of the solution = V = 113 mL = 0.113 L ( 1 mL = 0.001 L)

Molarity of the solution :

=\frac{0.1020 mol}{0.113 L}=0.903 M

[Molality]=\frac{\text{Moles of solute}}{\text{Mass of solvent(kg)}}

Moles of  phosphoric acid = 0.1020 mol

Mass of solvent(water) = m =100.0 g = 0.100 kg ( 1 g = 0.001 kg)

Molality of the solution :

=\frac{0.1020 mol}{0.100 kg}=1.02 mol/kg

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Order the various instruments used for measuring water in this experiment (balances, graduated cylinders, beaker and pipette) fr
lara [203]

Answer:

(Most accurate) pippete>graduated cylinder>beaker>balance (Least accurate)

Explanation:

  1. <em>Most accurate. A pipette prived the most accurate method for delivering a known volume of solution, for example, a 10mL transfer pipette has an accuracy of ±0.02mL</em>
  2. A graduated cylinder is specifically used to deliver a known volume, its typical accuracy is ±1%, this means that a 100ml graduated cylinder is accurate to ±1mL.
  3. A beaker is a multipurpose cylindrical glass mainly used to hold liquids. Even though they are graduated, these marks are an estimation, the beaker's accuracy is around 10%.
  4. Least accurate. A balance measures an object's mass, even though water's density is close to 1, a balance is not the ideal equipment to measure volume, its capacity usually goes between 100-200grams and can measure mass to the nearest ±0.01mg to ±1mg.

I hope you find this information useful and interesting! Good luck!

4 0
3 years ago
g, Assuming the precipitate is totally insoluble in water, which aqueous ions will be present in the solution (collected in the
Allushta [10]

Answer:

Cl⁻, Na⁺, OH⁻

Explanation:

The titration is:

CuCl₂(aq) + 2 NaOH(aq) → Cu(OH)₂(s) + 2 NaCl(aq)

In solution, before the reaction, the ions are Cu²⁺ and Cl⁻. The addition of NaOH (Na⁺ + OH⁻) produce the precipitation of Cu²⁺ forming Cu(OH)₂(s). When you reach the equivalence point, there is no Cu²⁺ because precipitates completely. All OH⁻ ions reacts when are added but when Cu²⁺ is finished, excess OH⁻ ions still in solution helping to detect the equivalence point.

Thus, ions present after the equivalence point are:<em> Cl⁻, Na⁺</em> (Don't react, spectator ions), and <em>OH⁻</em>.

3 0
3 years ago
Which scientist arranged the elements in order of increasing atomic number, rather than increasing atomic mass?
pentagon [3]

Answer:

Henry Moseley

Explanation:

Dmitry Mendeleef and Lothar Meyer proposed a periodic table based on the atomic mass.

They stated a periodic law expressed as "chemical properties of elements are a periodic function of their atomic weights".

But, Henry Moseley in 1900s re-stated periodic law by changing the basis of the law from atomic weight to atomic number.

The present periodic law is stated as "the properties of elements are a periodic function of their atomic number".

6 0
2 years ago
Which of the following is NOT a variable property for a gas?
Alex_Xolod [135]
Mass, air has that. Since what fills up a balloon? A gas
Shape, it has no definite shape. This one is accurate, it has no definite shape, it takes the shape of the object it's in.
Volume, does air take up space? If it does then yep. Balloon example/
Density, yes it does, because it's tightly wounded up.

D
5 0
3 years ago
Read 2 more answers
Consider 2H2 + O2 → 2H2O. To produce 1.2 g water, how many grams of H2 are required? Report to the correct number of significant
Elden [556K]

Answer:

0.133 mol (corrected to 3 sig.fig)

Explanation:

Take the atomic mass of H=1.0, and O=16.0,

no. of moles = mass / molar mass

so no. of moles of H2O produced = 1.2 / (1.0x2+16.0)

= 0.0666666 mol

From the equation, the mole ratio of H2:H2O = 2:2 = 1:1,

meaning every 1 mole of H2 reacted gives out 1 mole of water.

So, the no, of moles of H2 required should equal to the no, of moles of H2O produced, which is also  0.0666666 moles.

mass = no. of moles x molar mass

hence,

mass of H2 required = 0.066666666 x (1.0x2)

= 0.133 mol (corrected to 3 sig.fig)

3 0
3 years ago
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