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3 years ago

10 points

Chemistry

1 answer:

kaheart [24]3 years ago

8 0

Answer:

False.

Explanation:

I am not completely sure, but I don't believe the earth is getting larger.

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PLEASE HELP URGENT ( photo included)

elena-14-01-66 [18.8K]

Answer:

Explanation:

4 0

3 years ago

We can see water change state, from ice to steam. This is a __________ change in matter. A) chemical B) combustion Eliminate C)

Gemiola [76]

Answer: Option (C) is the correct answer.

Explanation:

When chemical composition of a substance is not changing in a chemical reaction then it is known as a physical change.

For example, when water change state, from ice to steam then it means solid state is changing into gaseous state.

Therefore, it is a physical change.

And, a reaction which causes change in chemical composition is known as a chemical change.

For example, $Li + Cl \rightarrow LiCl$

Thus, we can conclude that we can see water change state, from ice to steam. This is a physical change in matter.

4 0

3 years ago

A stone is dropped from the roof of a building; 2.00s after that, a second stone is thrown straight down with an initial speed o

Brut [27]

A) -0.5(9.8)*t^2 = -25(t-2) - 0.5(9.8)(t-2)^2
-4.9t^2 = -25t + 50 - 4.9(t^2-4t+4)
0 = -25t+50+19.6t - 19.6
5.4t = 30.4
t = 5.62962963 s

b) h = -4.9(5.62962963)^2
h = -155.2943759
the building is 155.2943759 m high

c) speed 0of first stone
= at
= 9.8*5.62962963
= 55.17037037 m/s
speed of second stone
= v + at
= 25+9.8*3.62962963
= 60.57037037 m/s

7 0

3 years ago

Sometimes in lab we collect the gas formed by a chemical reaction over water (see sketch at right). This makes it easy to isolat

ad-work [718]

Answer:

The correct answer is 0.00582 grams.

Explanation:

In order to solve the question, let us consider the vapor pressure of H2O, as hydrogen gas is collected over water, therefore, we have to consider the vapor pressure of water in the given case. Let us assume that the pressure is 760 torr or 1 atm.

It is known that the vapor pressure of water at 40 degree C is 53.365 torr (Based on the data).

Therefore, the pressure of H2 will be,

P = 760-55.365 = 704.635 torr or 704.635/760 = 0.9272 atm

The volume of the hydrogen gas collected in the tube is 80 ml or 0.08 L

Temperature in Kelvin will be 40+273 = 313 K

To calculate the moles of hydrogen (H2) gas, there is a need to use the ideal gas equation, that is, PV= nRT, in this R is the gas constant, whose value is 0.0821 L atm/molK, and n is the moles of the gas.

By inserting the values in the equation we get:

PV = nRT

n = PV/RT = 0.9272 *0.08 / 0.0821 * 313

n = 0.00289 moles

The mass of H2 will be moles * molar mass = 0.00289 * 2.016

= 0.00582 grams.

7 0

3 years ago

hurry please! avogadro's law relates the volume of a gas to the number of moles of gas when temperature and pressure are constan

DIA [1.3K]

Answer:

Option B. 4 moles of the gaseous product

Explanation:

Data obtained from the question include:

Initial volume (V1) = V

Initial number of mole (n1) = 2 moles

Final volume (V2) = 2V

Final number of mole (n2) =..?

Applying the Avogadro's law equation, we can obtain the number of mole of the gaseous product as follow:

V1/n1 = V2/n2

V/2 = 2V/n2

Cross multiply

V x n2 = 2 x 2V

Divide both side by V

n2 = (2 x 2V)/V

n2 = 2 x 2

n2 = 4 moles

Therefore, 4 moles of the gaseous product were produced.

5 0

3 years ago