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2 years ago

If 110. grams of potassium carbonate (K2CO3) is dissolved into 300. mL of solution, what is the molarity of the solution?

Chemistry

2 answers:

Ivan2 years ago

7 0

Answer:

2.7 M

Explanation:

M=moles of solute/volume of solution (L)

First, you need to calculate the number of moles using the given mass and the molar mass.

110 g138.205 g/mol=0.80 mol

Then, you can solve for molarity using the molarity equation.

M=0.80 mol0.300 L=2.7 M

Remember, you need to convert mL to L before you can calculate molarity.

il63 [147K]2 years ago

6 0

Answer:

2.65 M

Explanation:

Convert grams of K₂CO₃ to moles. The molar mass is 138.205 g/mol.

(110 g)/(138.205 g/mol) = 0.796 mol

Convert milliliters of solution to liters.

300 mL = 0.300 L

Divide moles of K₂CO₃ by liters of solution.

0.796 mol/0.300 L = 2.65 mol/L = 0.265 M

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Explain why neither the oil nor the glass fiber interferes with the diffraction pattern of the crystal.

SVEN [57.7K]

It's because The oil and the glass fibers do not interfere with X-ray crystallographic measurements because only one is crystalline.
Glass fibers have a low absorbance for X-rays and is not crystalline. Because of this, glass fibers will not interfere with X-Ray patterns. Oil, on the other hand, could be considered as crytalline.

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2 years ago

Select the correct answer. A student places a sample of white sodium bicarbonate powder in a test tube and heats it. The student

inessss [21]

Answer is: D. It is not sodium bicarbonate.

Balanced chemical reaction of heating sodium bicarbonate: 2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O.

This is chemical change (chemical reaction), because new substances are formed (sodium carbonate, carbon(IV) oxide and water), the atoms are rearranged, so there is no sodium bicarbonate (NaHCO₃) in the test tube.

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2 years ago

The highest principal enegy level of period 2 elements is 2. Period 3 elements all have six 3p electrons. Period 4 elements have

Dmitrij [34]

Explanation:

The highest principal energy level of period 2 elements is 2. (True)

The highest principle energy level of elements of any period is equal to period number. So the given statement is true.

Period 3 elements all have six 3p electrons – (False)

For example, sodium and sulfur are period 3 elements but do not contain six 3p electrons. Only Argon of period possesses six p-electrons.

Period 4 elements have an inner electron configuration of [Ar]- (True)

Atomic number of elements belonging to period 4 have atomic number more than 18 (atomic number of Ar). So they must have an inner electron configuration of [Ar]

The valence electrons of group 5A elements are in the 6s subshell – [FALSE]

Elements of group 5A are nitrogen, arsenic, antimony and bismuth. They are p-block elements. Therefore, valence electrons are present in p-subshell.

Group 8A elements have full outer principal s and p subshells –(True)

Group 8A elements are also known as noble gas element. Octets of noble gases are complete and hence, have full outer principal s and p subshells.

The valence electrons of group 2A elements are in an s subshell – (True)

Elements of group 2A are barium, magnesium, calcium, etc. They belong to s-block elements. Therefore, their valence electrons will be in s-subshell.

The highest principal energy level of period 3 elements is 4 – (False)

The highest principle energy level of elements of any period is equal to period number.

For example, sodium is present in 3rd period, so its principle quantum number will be 3.

Period 5 elements have an inner electron configuration of [Xe] – (False)

Period 5 elements have an inner electron configuration of [Kr]. The first member of this period is rubidium. 37 and that of Kr is 36.

6 0

2 years ago

The table above summarizes data given to a student to evaluate the type of change that took place when substance X was mixed wit

Tamiku [17]

The question is incomplete, the complete question is;

The table above summarizes data given to a student to evaluate the type of change that took place when substance X was mixed with water. The student claimed that the data did not provide enough evidence to determine whether a chemical or physical change took place and that additional tests were needed. Which of the following identifies the best way to gather evidence to support the type of change that occurred when water and Xwere mixed?

A. Measuring the melting point of the mixture of water and X

B. Adding another substance to the mixture of water and X to see whether a solid forms

C Measuring and comparing the masses of the water, X, and the mixture of water and X

D Measuring the electrical conductivities of X and the mixture of water and X

Answer:

D Measuring the electrical conductivities of X and the mixture of water and X

Explanation:

Unfortunately, I am unable to reproduce the table here. However, from the table, the temperature of the of the mixture of the solid X and water was 101.6°C. This is above the boiling point of water and way below the temperature of the solid X.

This goes a long way to suggest that there was some kind of interaction between the water and X which accounted for the observed temperature of the system of X in water.

The only way we can be able to confirm if X actually dissolved in water is to measure the conductivity of the water. dissolved solids increase the conductivity of water.

6 0

2 years ago

The nucleoside adenosine exists in a protonated form with a pKa of 3.8. The percentage of the protonated form at pH 4.8 is close

Natasha_Volkova [10]

Answer:

Ok:

Explanation:

So, you can use the Henderson-Hasselbalch equation for this:

pH = pKa + log( $A^-/HA$ ) where A- is the conjugate base of the acid. In other words, A- is the deprotonated form and HA is the protonated.

We can solve that

1 = log( $A^-/HA\\$ ) and so 10 = $A^-/HA$ or 10HA = A-. For every 1 protonated form of adenosine (HA), there are 10 A-. So, the percent in the protonated form will be 1(1+10) or 1/11 which is close to 9 percent.

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2 years ago