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3 years ago

Answer ASAP 30 points!! Why do elements and compounds qualify as pure substances?

Chemistry

2 answers:

AlladinOne [14]3 years ago

8 0

Answer:

Elements are made of only one kind of atom. ... The molecule is made up of two or more kinds of atoms. There is no physical change that can separate the compounds into more than one kind of substance. This makes a compound a pure substance.

Explanation:

MatroZZZ [7]3 years ago

3 0

Elements are made of only one kind of atom. The molecule is made up of two or more kinds of atoms. There is no physical change that can separate the compounds into more than one kind of substance. This makes a compound a pure substance.

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A silver sphere has a mass of 5.492 g and a diameter of 10.0 mm. What is the density of silver metal in grams per cubic centimet

Blizzard [7]

Answer:

Explanat $\rho=10.5\frac{g}{cm^3}$ ion:

Hello,

In this case, considering the given diameter which is related to a radius of 5.0 mm and the formula for the calculation of the volume of the sphere, its volume in cubic centimeters (5.00 mm = 0.5 cm) is then:

$V=\frac{4}{3} \pi r^3=\frac{4}{3}*\pi*(0.5cm)^3\\\\V=0.524cm^3$

In such a way, the density turns out:

$\rho =\frac{m}{V} =\frac{5.492g}{0.048m^3} \\\\\rho=10.5\frac{g}{cm^3}$

Best regards.

8 0

3 years ago

A student is asked to standardize a solution of barium hydroxide. He weighs out 0.978 g potassium hydrogen phthalate (KHC8H4O4,

Sav [38]

Answer:

(A) 0.129 M

(B) 0.237 M

Explanation:

(A) The reaction between potassium hydrogen phthalate and barium hydroxide is:

2HA + Ba(OH)₂ → BaA₂ + 2H₂O

Where A⁻ is the respective anion of the monoprotic acid (KC₈H₄O₄⁻).

We convert mass of phthalate to moles, using its molar mass:

0.978 g ÷ 156 g/mol = 9.27x10⁻³ mol = 9.27 mmol

Now we convert mmol of HA to mmol of Ba(OH)₂:

9.27 mmol HA * $\frac{1mmolBa(OH)_{2}}{2mmolHA}$ = 6.64 mmol Ba(OH)₂

Finally we calculate the molarity of the Ba(OH)₂ solution:

6.64 mmol / 35.8 mL = 0.129 M

(B) The reaction between Ba(OH)₂ and HCl is:

2HCl + Ba(OH)₂ → BaCl₂ + 2H₂O

So the moles of HCl that reacted are:

17.1 mL * 0.129 M * $\frac{2mmolHCl}{1mmolBa(OH)_2}$ = 4.41 mmol HCl

And the molarity of the HCl solution is:

4.41 mmol / 18.6 mL = 0.237 M

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3 years ago

If an endothermic reaction occurs in solution, the temperature of the solution will

Ahat [919]

Answer:

increase

Explanation:

because in endothermic reaction heat is absorbed

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3 years ago

Write the nuclear symbol for the neutral atom shown. 5 protons, 6 neutrons, 5 electrons. nuclear symbol:

OLga [1]

Answer:

Explanation:

the element is boron, therefore B is the symbol

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2 years ago

Why does the concentration of a product increase as the amount of the reactant decreases? (More 10+ pt questions on profile)

skad [1K]

As reactant concentration decreases, the forward. reaction slows. As product concentration increases, the reverse reaction becomes faster. The forward. reaction will continue to slow and the reverse reaction will continue to increase until they are the same.Then the situation will be at equilibrium.

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3 years ago