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2 years ago

Help me answer this chemistry question. thank you!

Chemistry

1 answer:

Leona [35]2 years ago

7 0

Answer:

A. How much decay happens in each flashlight

Explanation:

In an experiment, the DEPENDENT OR RESPONDING VARIABLE is the variable that responds to changes being made to another variable called Independent variable. It is the variable that is measured by an experimenter.

In this question, an experiment was carried out to research the effect of sunlight on plastic decay. Three plastic flashlights were used for this experiment in which one was placed in a dark closet (control), and the others were placed in light at different times or intervals. However, the variable being measured or assessed is the decay of each flashlight. This means that "HOW MUCH DECAY HAPPENS IN EACH FLASHLIGHT" is the dependent variable.

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Q1. Which reaction represents the half-reaction of lead (Pb) and the SRP value that could be found on an electric potential tabl

iris [78.8K]

The reaction that represents the half-reaction of lead Pb is
    Pb2+(aq) + 2e- → Pb(s)
and the SRP value on electric potential table is -0.13V.

To find the overall potential of a reaction, two half reactions can be added
together:
Oxidation:           Fe(s) → Fe2+(aq) + 2e-                     +0.44V
Reduction:          Pb2+(aq) + 2e- → Pb(s)                       - 0.13 V
Overall reaction: Fe(s) + Pb2+(aq) → Pb(s) + Fe2+(aq)    +0.31V

This positive voltage for the overall reaction is spontaneous.

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3 years ago

Why can't antibiotics be used on viruses?

kotykmax [81]

It can't be a viruses because it's a antibiotics

6 0

2 years ago

What volume of 0.305 m agno3 is required to react exactly with 155.0 ml of 0.274 m na2so4 solution? hint: you will want to write

LuckyWell [14K]

The balanced chemical equation for reaction of $AgNO_{3}$ and $Na_{2}SO_{4}$ is as follows:

$2 AgNO_{3}+Na_{2}SO_{4}\rightarrow 2NaNO_{3}+Ag_{2}SO_{4}$

From the balanced chemical equation, 2 mol of $AgNO_{3}$ reacts with 1 mol of $NaNO_{3}$ .

First calculating number of moles of $NaNO_{3}$ as follows:

$M=\frac{n}{V}$

On rearranging,

$n=M\times V$

Here, M is molarity and V is volume. The molarity of $NaNO_{3}$ is given 0.274 M or mol/L and volume 155 mL, putting the values,

$n=0.274 mol/L\times 155\times 10^{-3}mL=0.04247 mol$

Since, 1 mol of $NaNO_{3}$ reacts with 2 mol of $AgNO_{3}$ thus, number of moles of $AgNO_{3}$ will be $2\times 0.04247 mol=0.08494 mol$ .

Now, molarity of $AgNO_{3}$ is given 0.305 M or mol/L thus, volume can be calculated as follows:

$V=\frac{n}{M}=\frac{0.08494 mol}{0.305 mol/L}=0.2785 L=278.5 mL$

Therefore, volume of $AgNO_{3}$ is 278.5 mL.

4 0

3 years ago

1.) Examine the scenario.

Phantasy [73]

1) The answer is: Energy must have been absorbed from the surrounding environment.

There are two types of reaction:

1) Endothermic reaction (ΔH > 0, chemical reaction that absorbs more energy than it releases). In endothermic reactions heat is reactant.

Because products have higher energy, this example is endothermic reaction.

2) Exothermic reaction (chemical reaction that releases more energy than it absorbs).

2) The answer is: A reversible reaction contains a forward reaction, which occurs when reactants form products, and a reverse reaction, which occurs when products form reactants.

For example, balanced reversible chemical reaction: N₂ + 3H₂ ⇄ 2NH₃.

Nitrogen and hydrogen are reactants and ammonia is product of reaction. Reaction goes in both direction. Ammonia is synthesized from nitrogen and hydrogen and ammonia decomposes on nitrogen and hydrogen.

The amount of substance of reactants and products of reaction do not change when chemical reaction is in chemical equilibrium.

In a chemical reaction, chemical equilibrium is the state in which both reactants and products are present in concentrations which not change with time. Speed of direct and irreversible chemical reaction are equal

3) The answer is: The reaction rate of the forward reaction would increase in order to decrease the number of particles.

According to Le Chatelier's Principle the position of equilibrium moves to counteract the change.

The equilibrium shift to the right, so more product (ammonia) will be produced.

There are less molecules of ammonia than molecules of hydrogen and nitrogen. For every two molecules of ammonia, there are four molecules of hydrogen and nitrogen.

4) The answer is: The increase in energy will cause the reactants' particles to move faster, which will increase their temperature and lead to a faster reaction rate.

The reaction rate is the speed at which reactants are converted into products.

The collision theory states that a certain fraction of the collisions (successful collisions) cause significant chemical change.

The successful collisions must have enough energy (activation energy).

Chemical bonds are broken and new bonds are formed.

Particles are in constant, random motion and possess kinetic energy, molecules faster and have more collisions.

5) The answer is: When a reaction is at chemical equilibrium, a change in the system will cause the system to shift in the direction that will balance the change and help the reaction regain chemical equilibrium.

For example, chemical reaction: heat + NH₄⁺ + OH⁻ ⇄ NH₃ + H₂O.

According to Le Chatelier's Principle, the position of equilibrium moves to counteract the change, because heat is increased, system consume that heat, so equilibrium is shifted to right, by decreasing concentration of reactants and increasing concentration of product.

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3 years ago

At room temperature (20°C} and pressure, the density of air is 1.189 g/L. An object will float in air if its density is less tha

Alekssandra [29.7K]

Explanation:

$Density =\frac{Mass}[Volume}$

Density of the air ,d= 1.189 g/L

(a) Density of the evacuated ball

Mass of the ball ,m = 0.12 g

Volume of the ball = $V=560 cm^3=560 ml=0.560 L$

$D =\frac{0.12 g}{0.560 L}=0.214 g/L$

D<d, teh evacuated ball will flaot in air.

(b) Density of the evacuated ball D = 0.214 g/L

Density of carbon dioxide gas = $d_1=1.830 g/L$

Mass of the carbon dioxide gas :

$1.830 g/L\times 0.560 L=1.0248 g$

Total density of filled ball with carbon dioxide gas:

$\frac{0.12 g+1.0248 g}{0.560 L}==2.044 g/L$

The ball filled with carbon dioxide will not float in the air because total density of filled ball is greater than the density of an air.

(c) Density of the evacuated ball D = 0.214 g/L

Density of hydrogen gas = $d_2=0.0899 g/L$

Mass of the hydrogen gas :

$1.830 g/L\times 0.560 L=0.050344 g$

Total density of filled ball with hydrogen gas:

$\frac{0.12 g+0.050344 g}{0.560 L}==0.3041 g/L$

The ball filled with hydrogen will float in the air because total density of filled ball is lessor than the density of an air.

(d) Density of the evacuated ball D = 0.214 g/L

Density of oxygen gas = $d_3=1.330 g/L$

Mass of the oxygen gas :

$1.330 g/L\times 0.560 L=1.7448 g$

Total density of filled ball with oxygen gas:

$\frac{0.12 g+1.7448 g}{0.560 L}=1.5442 g/L$

The ball filled with oxygen will not float in the air because total density of filled ball is greater than the density of an air.

(e) Density of the evacuated ball D = 0.214 g/L

Density of nitrogen gas = $d_4=1.165 g/L$

Mass of the nitrogen gas :

$1.165 g/L\times 0.560 L=0.6524 g$

Total density of filled ball with nitrogen gas:

$\frac{0.12 g+0.6524 g}{0.560 L}==1.3792 g/L$

The ball filled with nitrogen will not float in the air because total density of filled ball is greater than the density of an air.

f) Mass must be added to sink the ball = m

Density of ball > Density of the air ; to sink the ball.

$\frac{0.12g +m}{0.560L}>1.189 g/L$

m > 0.54584 g

For any case weight added to ball to make it sink in an air should be grater than the value of 0.54584 grams.

5 0

2 years ago