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3 years ago

What is cement and who invented it?

Chemistry

1 answer:

Sonja [21]3 years ago

5 0

Answer:

Cement is a combination of calcium, silicone, aluminum, iron and lots of other ingredients to make side walks, home made crafts, etc. The person who invented concrete is Joseph Aspdin.

Explanation:

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Before a bond breaks in a chemical reaction, what happens

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Energy is being released

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How to keep pipes from freezing during power outage?.

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Answer: <em>Running water, even at a trickle, helps prevent pipes from freezing. If you decide to use fuel-burning equipment, such as a kerosene heater, ensure it is vented to outside and kept clear of any vents. Keep garage doors closed if there are water supply lines in the garage.</em>

Explanation:

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How can you separate a mixture containing two different liquids? filtration evaporation distillation magnetic attraction

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4 years ago

How to balance lead and silver acetate yields lead (||) acetate and silver

arsen [322]

The given elements put into an equation using their symbols are as follows:
Pb + $AgC_{2}H_{3}O_{2}$ = $Pb(II){(C_{2}H_{3}O_{2})_2}$ + Ag

Since there are 2 Pb on the right side of the equation, you would change the coefficient of Pb on the left side to 2:
2Pb + $AgC_{2}H_{3}O_{2}$ = $Pb(II){(C_{2}H_{3}O_{2})_2}$ + Ag

Since there are 2 Acetate on the right side of the equation, you would change the coefficient of Silver Acetate on the left side to 2:
2Pb + $2AgC_{2}H_{3}O_{2}$ = $Pb(II){(C_{2}H_{3}O_{2})_2}$ + Ag

Now there are 2 Silver on the left side, so you change the coefficient of Silver on the right side to 2:
2Pb + $2AgC_{2}H_{3}O_{2}$ = $Pb(II){(C_{2}H_{3}O_{2})_2}$ + 2Ag

That is your final equation

The coefficients are 2 + 2 = 1 + 2

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3 years ago

Decide which of the following statements are True and which are False about equilibrium systems:A large value of K means the equ

ivanzaharov [21]

Answer:

a. True

b. False

c. True

d. False

e. False

Explanation:

A. (true) The equilibrium constant K is defined as

$\frac{Products}{reagents}$

In any case

aA +Bb ⇌ Cd +dD

where K is:

$K= \frac{[C]^{c}[D]^{d}}{[A]^{a}[B]^{b}}$

A large value on K means that the concentration of products is bigger than the concentrations of reagents, so the forward reaction is favored, and the equilibrium lies to the right.

B. (False) When we work with gases, we use partial pressure to make calculations in the equilibrium, so we estimate Kp as:

$Kp= \frac{(P_{C})^{c}(P_{D})^{d}}{(P_{A})^{a}(P_{B})^{b}}$

Using the ideal gas law, we can get a relationship between K and Kp

Pv=nRT where $P=\frac{n}{v}*RT$ we know that $\frac{n}{v}$ is the molar concentration. When we replace P in the expression for Kp we get:

$Kp= \frac{[C]^{c}*(RT)^{c}[D]^{d}*(RT)^{d}}{[A]^{a}*(RT)^{a}[B]^{b}*(RT)^{b}}$

Reorganizing the equation:

$Kp= \frac{[C]^{c}[D]^{d}}{[A]^{a}[B]^{b}}*\frac{(RT)^{c+d}}{(RT)^{a+b}}$

We can see K in the expression

$Kp= K*(RT)^{c+d-a-b}$

Delta n = c+d-a-b

$Kp= K*(RT)^{delta n}$

For the reaction

$H_{2}(g) + F_{2}(g)-- equilibrium---2HF(g)$

Delta n = 2-1-1=0

$Kp= K*(RT)^{0}$

So Kp=K in this case.

C. (true) The value of K just depends on the temperature that’s why changing the among of products won’t have any effect on its value.

D. (false) as we can see this reaction involve a heterogeneous system with solids and gases. For convention the concentration for solids and liquids can be considered constant during the reaction that’s why they’re not include in the calculation for the equilibrium constant. Taking this into account the expression for the equilibrium for this reaction is:

$CaCO_{3}(s)---equilibrium----CaO(s) + CO_{2}(g)$

$K= [CO_{2}]$

So we can see that $[CaCO_{3}]$ is not include in the expression.

E. (False) The equilibrium is defined as the point where the rate of the forward reaction is the same to the rate of the reverse reaction. The value of K is telling you which reaction is favored but the rate of both reactions is the same in this point. (see picture)

3 0

3 years ago