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2 years ago

Which observation illustrates the law of conservation of mass?

2 answers:

const2013 [10]2 years ago

8 0

The conservation of mass states that the total mass of reactants present before the reaction occurs is equal to the total mass of products after the reaction. From the choices, the second choice deems fit for the description of the law.

alekssr [168]2 years ago

4 0

Answer: When 3 g of carbon reacts with 8 g of oxygen, 11 g of carbon dioxide is produced.

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

$C+O_2\rightarrow CO_2$

Given: mass of carbon = 3 g

mass of oxygen = 8 g

Mass of products = Mass of carbon dioxide = 11 g

Mass or reactant = mass of carbon + mass of oxygen = 3 g + 8 g = 11g

Thus the total mass of reactants is equal to the total mass of products.

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Assume the volume of the crew cabin is 74,000 L. The pressure is maintained at around 1.00 atm, ideally with an 80% nitrogen and

hjlf

Answer:

The number of moles of oxygen present in the crew cabin at any given time is 615.309 moles

Explanation:

The given parameters are;

Volume of the crew cabin = 74,000 L

Pressure of the crew cabin = 1.00 atm

Percentage of nitrogen in the mixture of gases in the cabin = 80%

Percentage of oxygen in the mixture of gases in the cabin = 20%

Temperature of the cabin = 20°C = 293.15 K

Therefore, volume of oxygen in the crew cabin = 20% of 74,000 L

Hence, volume of oxygen in the crew cabin = $\frac{20}{100} \times 74,000 \, L = 14,800 \, L$

From the universal gas equation, we have;

$n = \frac{P \times V}{R \times T}$

Where:

n = Number of moles of oxygen

P = Pressure = 1.00 atm

V = Volume of oxygen = 14,800 L

T = Temperature = 293.15 K

R = Universal Gas Constant = 0.08205 L·atm/(mol·K)

Plugging in the values, we have;

$n = \frac{1 \times 14,800 }{0.08205 \times 293.15 } = 615.309 \, moles$

The number of moles of oxygen present in the crew cabin at any given time = 615.309 moles.

3 0

3 years ago

Nitric acid (HNO3) is a strong acid, and it is titrated with a standard solution of sodium hydroxide (NaOH), a strong base. Whic

aev [14]

C. pH = 7.0

i just had the test

4 0

3 years ago

Read 2 more answers

A mixture of water and graphite is heated to 600 K in a 1 L container. When the system comes to equilibrium it contains 0.17 mol

Kryger [21]

Answer:

0.44 moles

Explanation:

Given that :

A mixture of water and graphite is heated to 600 K in a 1 L container. When the system comes to equilibrium it contains 0.17 mol of H2, 0.17 mol of CO, 0.74 mol of H2O, and some graphite.

The equilibrium constant $K_c= \dfrac{[CO][H_2]}{[H_2O]}$

The equilibrium constant $K_c= \dfrac{(0.17 )(0.17)}{0.74}$

The equilibrium constant $K_c= 0.03905$

Some O2 is added to the system and a spark is applied so that the H2 reacts completely with the O2.

The equation for the reaction is :

$H_2 + \dfrac{1}{2}O_2 \to H_2O \\ \\ 0.17 \ \ \ \ \ \ \ \ \ \to0.17$

Total mole of water now = 0.74+0.17

Total mole of water now = 0.91 moles

Again:

$K_c= \dfrac{[CO][H_2]}{[H_2O]}$

$0.03905 = \dfrac{[0.17+x][x]}{[0.91 -x]}$

0.03905(0.91 -x) = (0.17 +x)(x)

0.0355355 - 0.03905x = 0.17x + x²

0.0355355 +0.13095 x -x²

x² - 0.13095 x - 0.0355355 = 0

By using quadratic formula

x = 0.265 or x = -0.134

Going by the value with the positive integer; x = 0.265 moles

Total moles of CO in the flask when the system returns to equilibrium is :

= 0.17 + x

= 0.17 + 0.265

= 0.435 moles

=0.44 moles (to two significant figures)

3 0

3 years ago

Jamie is measuring the mass of one mole of carbon. She measures the mass 4 times, achieving the following measurements: 11.86 g,

azamat

This is an incomplete question, here is a complete question.

Distinguish between Accuracy and Precision Question Jamie is measuring the mass of one mole of carbon. She measures the mass 4 times, achieving the following measurements: 11.86 g, 11.87 g, 11.89 g, and 11.90 g. If the accepted value of one mole of carbon is 12.11 g, how can Jamie's measurements best be described?

Select the correct answer below:

Jamie's measurements are both precise and accurate,

Jamie's measurements are accurate but not precise.

Jamie's measurements are precise but not accurate,

Jamie's measurements are neither precise nor accurate,

Answer : The correct option is, Jamie's measurements are precise but not accurate.

Explanation :

Accuracy : It is defined as the closeness of a measured value to a standard or known value.

For Example: If the mass of a substance is 50 kg and one person weighed 48 kg and another person weighed 55 kg. Then, the weight measured by first person is more accurate.

Precision : It is defined as the closeness of two or more measurements to each other.

For Example: If you weigh a given substance five times and you get 1.8 kg each time. Then the measurement is said to be precise.

Level of precision is determined by the maximum number of decimal places.

As we are given that:

The measurements are, 11.86, 11.87, 11.89 and 11.90

The accepted value is, 12.11

The average of these values = $\frac{11.86+11.87+11.89+11.90}{4}=11.88$

From this we conclude that, these measurements are close to each other that means they are precise. But the accepted value are not equal to average of four values that means they are not accurate.

Hence, the correct option is, Jamie's measurements are precise but not accurate.

7 0

3 years ago

Marijuana most abundant psychoactive chemical is delta-9- tetrahydrocannabinol or

Galina-37 [17]

<h2>Answer:</h2>

<u>Yes the statement is</u><u> True</u>

<h2>Explanation:</h2>

THC is a chemical which stands for delta-9-tetrahydrocannibinol or Δ-9-tetrahydrocannabinol (Δ-9-THC). This chemical is a cannabinoid molecule in marijuana or cannabis that has long been known as the main psychoactive ingredient in marijuana which means that it is the substance that causes users to experience the marijuana high. It can be detected in the blood up to 20 hours after ingestion, and it's stored in the body fat and organs for three to four weeks after ingestion.

7 0

3 years ago

Read 2 more answers