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3 years ago

Which of these is a characteristic of science?

Chemistry

2 answers:

jenyasd209 [6]3 years ago

5 0

The correct answer is D. It gives the same result when experiments are repeated.

Explanation:

Science refers to a system or discipline that aims at understanding phenomena that is testable mainly through multiple observations, hypotheses, and testing. Because of this, characteristics of science include that it is based on facts or ideas that have been proved, it is useful for answering testable questions and also the findings are replicable which means if tested multiple times same results would be obtained which proves phenomenons and events are facts and do not depend on opinions or personal views. Considering this, the one that is a characteristic of science is that "It gives the same result when experiments are repeated".

Ivahew [28]3 years ago

3 0

D. It gives the same results when experiments are repeated

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(2 KClO3 (s) → 2 KCl (s) + 3 O2 (g) ) If 165 mL of oxygen is produced at 30.0 °C and 90.0 kPa, what mass of KClO3 was decomposed

soldier1979 [14.2K]

Taking into account the reaction stoichiometry and ideal gas law, 0.48144 grams of KClO₃ was decomposed.

<h3>Reaction stoichiometry</h3>

In first place, the balanced reaction is:

2 KClO₃ → 2 KCl + 3 O₂

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

KClO₃: 2 moles
KCl: 2 moles
O₂: 3 moles

The molar mass of the compounds is:

KClO₃: 122.45 g/mole
KCl: 74.45 g/mole
O₂: 32 g/mole

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

KClO₃: 2 moles ×122.45 g/mole= 244.8 grams
KCl: 2 moles ×74.45 g/mole= 148.9 grams
O₂: 3 moles ×32 g/mole= 96 grams

<h3>Ideal gas law</h3>

The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:

P×V = n×R×T

where:

P is the gas pressure.
V is the volume that the gas occupies.
T is the temperature of the gas.
R is the ideal gas constant. The universal constant of ideal gases R has the same value for all gaseous substances.
n is the number of moles of the gas.

<h3>Number of O₂ produced.</h3>

165 mL of oxygen is produced at 30.0 °C and 90.0 kPa. This is, you know:

P= 90 kPa= 0.888231 atm (being 101.325 kPa= 1 atm)
V= 165 mL= 0.165 L (being 1000 mL= 1 L)
n= ?
R= 0.082 $\frac{atmL}{molK}$
T= 30 C= 303 K (being 0 C= 273 K)

Replacing in the ideal gas law:

0.888231 atm× 0.165 L = n× 0.082 $\frac{atmL}{molK}$ × 303 K

Solving:

n= (0.888231 atm× 0.165 L)÷ (0.082 $\frac{atmL}{molK}$ × 303 K)

<u><em>n= 0.0059 moles</em></u>

Finally, 0.0059 moles of oxygen is produced at 30 °C and 90 kPa.

<h3>Mass of KClO₃ required</h3>

The following rule of three can be applied: If by stoichiometry of the reaction 3 moles of O₂ are produced by 244.8 grams of KClO₃, 0.0059 moles of O₂ are produced by how much mass of KClO₃?

$mass of KClO_{3}= \frac{0.0059 moles of O_{2}x 244.8 grams of KClO_{3}}{3 moles of O_{2}}$

<u><em>mass of KClO₃= 0.48144 grams</em></u>

Finally, 0.48144 grams of KClO₃ was decomposed.

Learn more about

the reaction stoichiometry:

<u>brainly.com/question/24741074</u>

<u>brainly.com/question/24653699</u>

ideal gas law:

<u>brainly.com/question/4147359?referrer=searchResults</u>

4 0

2 years ago

Explain three path ways of respiration

Phantasy [73]

Answer:

Explanation:

1:faringe:es un conducto que permite la comunicación entre las fosas nasales (el paso del aire por la nasofaringe a la laringe) y la cavidad bucal

Laringe:es una cavidad formada por cartílagos que presenta una saliente comúnmente llamada "nuez" en la laringe se encuentra las cuerdas vocales que al vibrar con el aire produce la voz

Tráquea:es un conducto de doce centímetros de longitud,situado delante del estómago.la tráquea brinda una vía abierta al aire que entra y sale se los pulmones

6 0

3 years ago

Which answer below correctly identifies the type of change and the explanation when magnesium comes into contact with hydrochlor

Oliga [24]

Answer:

A chemical change because a temperature change occurred, the solid disappeared and a gas was produces

Explanation:

Magnesium reacts with hydrochloric acid releasing energy, and leading to the formation of magnesium chloride and hydrogen gas. This is represented by the equation below:

Mg₍s₎ + 2HCl₍aq)⇒ MgCl₂₍aq₎ + H₂₍g₎

5 0

4 years ago

Read 2 more answers

Which solute produces the highest boiling point in a 0.15 m aqueous solution?

saul85 [17]

In order to determine the increase in boiling point of a solvent due to the presence of a solute, we use the formula:

ΔT = Kb * m * i

Here, Kb is a property of the solvent, so remains constant regardless of the solute. Moreover, because the concentration m has been fixed, this will also not be considered. In order to determine which solute will have the greatest effect, we must check i, the van't Hoff factor.

Simply stated, i is the number of ions that a substance produces when dissolved. Therefore, the solute producing the most ions will be the one causing the greatest change in boiling point temperature.

6 0

3 years ago

Es un cambio natural o provocado, donde se produce energía para agua y dióxido de carbono: a)Precipitación. b)Fermentación c) Ef

Andre45 [30]

Answer:

d) Combustión.

Explanation:

¡Hola!

En este caso, dado que estamos enfocados en el concepto de cambio químico, el cual se caracteriza por exhibir un cambio en la composición e identidad de las sustancias iniciales (reactivos) a otras finales (productos).

Ahora bien, como se nos dice que los productos de este cambio químico son energía, agua y dióxido de carbono, inferimos que el nombre de este proceso es d) Combustión, por ejemplo la combustion del gas natural para calentar nuestras comidas en la cocina.

¡Saludos!

6 0

3 years ago