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3 years ago

In a chemical reaction, energy can be A. released. B. absorbed. C. released or absorbed. D. neither released nor absorbed.

2 answers:

4 0

C. released or absorbed.

When the energy is released the reaction is called exotermic reaction
When the energy is absorbed, the reaction is called endothermic reaction

An example of exotermic reaction is between water and H2SO4

USPshnik [31]3 years ago

4 0

Oof I was about to say the same answer.

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A 3.31-g sample of lead nitrate, Pb(NO3)2, molar mass = 331 g/mol, is heated in an evacuated cylinder with a volume of 2.53 L. T

Dahasolnce [82]

Answer:

0.486atm is the pressure of the cylinder

Explanation:

1 mole of Pb(NO₃)₂ descomposes in 4 moles of NO2 and 1 mole of O2. That is 1 mole descomposes in 5 moles of gas.

To find the pressure of the cylinder, we need to find moles of gas produced, and using general gas law we can determine the pressure of the gas:

Moles Pb(NO₃)₂ and moles of gas:

3.31g * (1mol / 331g) = 0.01 moles of Pb(NO₃)₂.

That means moles of gas produced is 0.05 moles.

Pressure of the gas:

Using PV = nRT

P = nRT/V

Where P is pressure (Incognite)

V is volume (2.53L)

R is gas constant (0.082atmL/molK)

T is absolute temperature (300K)

And n are moles of gas (0.05 moles)

P = 0.05mol*0.082atmL/molK*300K / 2.53L

P = 0.486atm is the pressure of the cylinder

3 0

3 years ago

No FILES PLZZ

Bumek [7]

Answer:

Converted to renewable ones

exhausted or depleted

5 0

2 years ago

Read 2 more answers

Give the volume indicated. Be sure to include all significant figures.

miskamm [114]

Answer: -

Explanation: -

From the diagram, we see that volume goes from 70 to 75 in 5 markings.

Each marking is for 1.

It is the most accuracy possible as there is no smaller marking.

Significant figures expresses the required amount of accuracy.

Thus the volume indicated from the diagram is 71 .

8 0

3 years ago

Read 2 more answers

The powder mixture (Cu, Al and Fe) = 10g was oxidized from sufficient chloride acid. 1) What are the possible reactions to the p

Mandarinka [93]

Answer:

1) 2Al + 6HCl ⟶ 2AlCl₃ + 3H₂

Fe + 2HCl ⟶ FeCl₂ + H₂

2) Cu = 2.5 g; Al = 3.5 g; Fe = 4.0 g

Explanation:

1) Possible reactions

2Al + 6HCl ⟶ 2AlCl₃ + 3H₂

Fe + 2HCl ⟶ FeCl₂ + H₂

2) Mass of each metal

a) Mass of Cu

The waste was the unreacted copper.

Mass of Cu = 2.5 g

b) Masses of Al and Fe

We have two relations :

Mass of Al + mass of Fe = 10 g - 2.5 g = 7.5 g

H₂ from Al + H₂ from Fe = 6.38 L at NTP

i) Calculate the moles of H₂

NTP is 20 °C and 1 atm.

$\begin{array}{rcl}pV & = & n RT\\\text{1 atm} \times \text{6.38 L} & = & n \times 0.08206 \text{ L}\cdot\text{atm}\cdot\text{K}^{-1}\text{mol}^{-1} \times \text{293.15 K}\\6.38 & = & 24.06n \text{ mol}^{-1} \\n & = & \dfrac{6.38}{24.06 \text{ mol}^{-1} }\\\\ & = & \text{0.2652 mol}\\\end{array}$

(ii) Solve the relationship

Let x = mass of Al. Then

7.5 - x = mass of Fe

Moles of Al = x/27

Moles of Fe = (7.5 - x)/56

Moles of H₂ from Al = (3/2) × Moles of Al = (3/2) × (x/27) = x /18

Moles of H₂ from Fe = (1/1) × Moles of Fe = (7.5 - x)/56

∴ x/18 + (7.5 - x)/56 = 0.2652

56x + 18(7.5 - x) = 267.3

56x + 135 - 18x = 267.3

38x = 132.3

x = 3.5 g

Mass of Al = 3.5 g

Mass of Fe = 7.5 g - 3.5 g = 4.0 g

The masses of the metals are Cu = 2.5 g; Al = 3.5 g; Fe = 4.0 g

4 0

3 years ago

A student conducts an experiment to determine how the temperature of water affects the time for sugar to dissolve. In each trial

V125BC [204]

The fact that the student used different amount of water (another independent variable) is wrong with the experimental design

WHAT ARE THE COMPONENTS OF AN EXPERIMENT?

An experiment aims at solving a scientific problem or answering a scientific question. An experiment should contain a variable being changed called INDEPENDENT VARIABLE and a variable being measured called DEPENDENT VARIABLE.

In an ideal experiment, only one independent variable should be used while every other variable should be kept constant. This is done so as not to affect the result of the experiment.

In the experiment conducted by the student in this question, two independent variables were used i.e. the different amount of water and the different temperatures. This is what is wrong about the experimental design.

In a nutshell, the fact that two independent variables were used by the student is what is wrong about the experimental design.

Learn more at: brainly.com/question/967776

8 0

3 years ago