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podryga [215]
2 years ago
9

An experiment in chm 2045 requires students to prepare a 1.0 M aqueous solution of potassium phosphate.Jennifer fills a 1.0 lite

r volumetric flask to the calibration line with water. She then weighs out 212.3 g of potassium phosphate and adds it to the volumetric flask.Joe weighs out 212.3 g of potassium phosphate and adds it to a 1.0 liter volumetric flask. He then fills the volumetric flask to the calibration line with water.Which student has correctly prepared a 1.0 M aqueous solution of potassium phosphate?
Chemistry
1 answer:
horrorfan [7]2 years ago
6 0

Answer:

Joe correctly prepared the solution.

Explanation:

When comparing both methods, we see that the mass of potassium phosphate weighed is the same for Jennifer and Joe, so that's not a factor.

The difference lies in the fact that Jennifer added the solid to 1.0 liters of water, so<u> the final volume is higher than 1.0 L</u>, that's why t<u>he concentration will be lower than 1.0 M</u>.

The final volume of Joe's solution is 1.0 L, that's why he prepared the solution correctly.

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If you compared 1 m solutions, was a 1 m nacl solution more or less hypertonic than a 1 m sucrose solution? what is your evidenc
igor_vitrenko [27]
When you say the solution is hypertonic, it means that the solution has a higher osmotic pressure. The formula for this is:

P = iMRT,
for strong electrolytes, i = number of ions. 
for nonelectrolytes, i = 1

1. The P for sucrose solution which is a nonelectrolyte (assuming room temp):
P = (1)(1m)(8.314 J/mol-K)(298 K)
P = 2477.572 Pa

The P for NaCl solution, which is a strong electrolyte:
P = (2)(1 m)(8.314)(298 K)
P = 4955.144 Pa

<em>So, that means that NaCl is more hypertonic than the sucrose solution.</em>

2. For the second question, the P for the combination of 1 m glucose (nonelectrolyte) and 1 m sucrose is:
P = (1)(1 m)(8.314)(298 K) + (1)(1)(8.314)(298 K) = 4955.144 Pa
<em>In this case, the osmotic pressures are now equal. It is not hypertonic, but isotonic.</em>

7 0
2 years ago
For the reaction PCl5(g) &lt;--&gt; PCl3(g) Cl2(g) at equilibrium, which statement correctly describes the effects of increasing
xenn [34]

The given question is incomplete. The complete question is :

For the reaction PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g) at equilibrium, which statement correctly describes the effects of increasing pressure and adding PCl_5, respectively

a) Increasing pressure causes shift to reactants, adding PCl_5 causes shift to products.

b) Increasing pressure causes shift to products ,adding PCl_5 causes shift to reactants.

c) Increasing pressure causes shift to products, adding PCl_5 causes shift to products.

d) Increasing pressure causes shift to reactants,adding PCl_5 causes shift to reactants

Answer: Increasing pressure causes shift to reactants, adding PCl_5 causes shift to products.

Explanation:

Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.

This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

For the given equation:

PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)

a)  If the pressure is increased, the volume will decrease according to Boyle's Law. Now, according to the Le-Chatlier's principle, the equilibrium will shift in the direction where decrease in pressure is taking place. As the number of moles of gas molecules is lesser at the reactant side. So, the equilibrium will shift in the left direction. i.e. towards reactants.

b) If PCl_5 is added, the equilibrium will shift in the direction where PCl_5 is decreasing. So, the equilibrium will shift in the right direction. i.e. towards products.

8 0
2 years ago
What types of compounds are CaCl2, Cu, C2H6, respectively.
mina [271]

Answer:

Ionic, metal, organic

Explanation:

In this case, we have to analyze each compound:

-) CaCl_2

In this compound, we have a non-metal atom (Cl) and a metal atom (Ca) . So, we will have a high electronegativity difference between these atoms, With this in mind, we will have an ionic bond. Ions can be produced:

CaCl_2~->~Ca^+^2~+~2Cl^-

The cation would be Ca^+^2 and the anion is Cl^-. So, we will have an <u>ionic compound.</u>

-) Cu

In this case, we have a single atom. If we check the periodic table we will find this atom in the transition metals section (in the middle of the periodic table). So, this indicates that Cu (Copper) is a <u>metal.</u>

-) C_2H_6

In this molecule, we have single bonds between carbon and hydrogen. The electronegativity difference between C and H are not high enough to produce ions. So, with this in mind, we will have covalent bonds. This is the main characteristic of <u>organic compounds. </u> (See figure 1)

5 0
2 years ago
The concept of resonance describes molecular structures Question 17 options: that have several different geometric arrangements.
kipiarov [429]

Answer:

that are formed from hybridized orbitals

Explanation:

The chemical concept of resonance is when a change in the position of the electrons occurs, without changing the position of the atoms.  

The structure obtained in the resonance will not be any of the previous ones, but a hybrid of resonance between those structures.

3 0
2 years ago
ethylene glycol used in automobile antifreeze and in the production of polyester. The name glycol stems from the sweet taste of
Luden [163]

<u>Answer:</u> The empirical and molecular formula for the given organic compound is CH_3O and C_4H_{12}O_4

<u>Explanation:</u>

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

C_xH_yO_z+O_2\rightarrow CO_2+H_2O

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of CO_2=9.06g

Mass of H_2O=5.58g

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

  • <u>For calculating the mass of carbon:</u>

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 9.06 g of carbon dioxide, \frac{12}{44}\times 9.06=2.47g of carbon will be contained.

  • <u>For calculating the mass of hydrogen:</u>

In 18g of water, 2 g of hydrogen is contained.

So, in 5.58 g of water, \frac{2}{18}\times 5.58=0.62g of hydrogen will be contained.

  • Mass of oxygen in the compound = (6.38) - (2.47 + 0.62) = 3.29 g

To formulate the empirical formula, we need to follow some steps:

  • <u>Step 1:</u> Converting the given masses into moles.

Moles of Carbon =\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{2.47g}{12g/mole}=0.206moles

Moles of Hydrogen = \frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.62g}{1g/mole}=0.62moles

Moles of Oxygen = \frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{3.29g}{16g/mole}=0.206moles

  • <u>Step 2:</u> Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.206 moles.

For Carbon = \frac{0.206}{0.206}=1

For Hydrogen  = \frac{0.62}{0.206}=3

For Oxygen  = \frac{0.206}{0.206}=1

  • <u>Step 3:</u> Taking the mole ratio as their subscripts.

The ratio of C : H : O = 1 : 3 : 1

Hence, the empirical formula for the given compound is C_1H_{3}O_1=CH_3O

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

n=\frac{\text{molecular mass}}{\text{empirical mass}}

We are given:

Mass of molecular formula = 124 amu = 124 g/mol

Mass of empirical formula = 31 g/mol

Putting values in above equation, we get:

n=\frac{124g/mol}{31g/mol}=4

Multiplying this valency by the subscript of every element of empirical formula, we get:

C_{(1\times 4)}H_{(3\times 4)}O_{(1\times 4)}=C_4H_{12}O_4

Thus, the empirical and molecular formula for the given organic compound is CH_3O and C_4H_{12}O_4

3 0
2 years ago
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