What did ancient astronomers not know about eclipses?

Answer:

TRUE ,hope it helped you

Explanation:

1.2 × 10²⁴ atoms C

Chemistry

Atomic Structure

Stoichiometry

Math

Pre-Algebra

Order of Operations: BPEMDAS

Step 1: Define

Identify variables

[Given] 24 g C

[Solve] atoms C

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of C: 12.01 g/mol

Step 3: Convert

Step 4: Check

Follow sig fig rules and round. We are given 2 sig figs.

1.2034 × 10²⁴ atoms C ≈ 1.2 × 10²⁴ atoms C

The correct question is: 10 kg of R-134a at 300 kPa fills a rigid container whose volume is 14 L. Determine the temperature and total enthalpy in the container. The container is now heated until the pressure is 600 kPa. Determine the temperature and total enthalpy when the heating is completed.

Answer: The temperature is [tex]21.6^{o}C[/tex] and total enthalpy when the heating is completed is 300 kJ.

Explanation:

Given: Mass = 10 kg

Volume = 14 L

Final pressure = 600 K

First, convert volume from L to [tex]m^{3}/kg[/tex] as follows.

[tex]v_{1} = \frac{14 \times 10^{-3}}{10}\\= 0.0014 m^{3}/kg[/tex]

According to the R-134a tables at 300 kPa and [tex]0.0014 m^{3}/kg[/tex].

[tex]h_{1}[/tex] = 54.6 kJ/kg

[tex]T_{sat}[/tex] = 0.7 C

[tex]u_{1}[/tex] = 54.1 kJ/kg

Now, at the state 2 [tex]p_{2}[/tex] = 600 kPa and [tex]v_{2} = v_{1} = 0.0014 m^{3}/kg[/tex]

This means that the final temperature at state 2 is [tex]T_{2} = T_{sat} = 21.6^{o}C[/tex]

Hence, the change in enthalpy is calculated as follows.

[tex]\Delta H = m(h_{2} - h_{1})\\= 10(84.6 - 54.6)\\= 300 kJ[/tex]

The first law is applied to transfer the heat transfer as follows.

[tex]Q = m(u_{2} - u_{1})\\= 10(83.8 - 54.1) kJ\\= 297 kJ[/tex]

Thus, we can conclude that the temperature is [tex]21.6^{o}C[/tex] and total enthalpy when the heating is completed is 300 kJ.

Answer:

The correct answer is 40.7 grams.

Explanation:

Based on the given information, the volume of copper sulfate added to the solution is 255 ml or 0.255 L. The molarity of copper sulfate is not given, so let us consider it to be 1 M, which can also be written as 1 moles per liter.

The moles of copper sulfate can be determined by using the formula,

Moles = Molarity * Volume in Liters

Moles of CuSO4 = 1 moles/Liter * 0.255 L

Moles of CuSO4 = 0.255 moles

The mass of CuSO4 added in the solution will be,

Mass of CuSO4 = Moles * Molecular mass

= 0.255 moles * 159.609 grams per mole

= 40.7 grams.

Answer:

The correct answer is 1.21 L.

Explanation:

Based on the given information, the reaction will be,

CS2 (l) + 3Cl2 (g) ⇒ CCl4 (l) + S2Cl2 (l)

By using the standard values of the substances, the standard enthalpy of the reaction is,

ΔH° = [(-139.5) + (-58.5) – 0 – (87.3)] kJ/mol

= -285.3 kJ/mol

The amount of heat evolved for 3 moles of chlorine reacted us 285.3 kJ.

Now the number of moles of chlorine needed to react to produce 5.00 kJ is,

= 5.00 kJ × 3 mol Cl2/285.3 kJ

= 0.0526 mol Cl2

Now the volume of chlorine gas at 27degree C and 812 mmHg will be,

Volume = 0.0526 mol Cl2 × 0.0821 Latm/mol K × 300 K/ 1.07 atm

= 1.21 L

Explanation:

2H2O and 0.722g of Na3PO4.12H20 mix with water forming 500 mL of solution, how many grams of Ba3(. ... Forming 500 ML Of Solution, How Many Grams Of Ba3(PO4)2 Precipitate?

When 0.421 g of BaCl₂ · 2 H2O and 0.722g of Na₃PO₄ · 12 H₂O mix with water forming 500 mL of solution then 0.003 mol/L of Ba₃(PO4)₂ precipitate.

Stoichiometry is an important concept which helps us use the balanced chemical equation to measures the amount of reactants and products.

Molarity of solution is the number of moles of solute per liter of solution. Molarity is also called Molar Concentration.

Molarity (M) = [tex]\frac{\text{number of moles}}{\text{volume of solution (in liters)}}[/tex]

Number of moles = [tex]\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

First we have to write the balanced chemical equation

2Na₃PO₄ · 12 H₂O + 3BaCl₂ · 2 H2O → Ba₃(PO4)₂ + 6 NaCl + 30 H₂O

Here 3 moles of BaCl₂ · 2 H2O produce 1 mole of Ba₃(PO4)₂

So,

Number of moles of BaCl₂ · 2 H2O = [tex]\frac{\text{Mass of}\ BaCl_2 . 2H_2O}{\text{Molar mass of}\ BaCl_2. 2H_2O}[/tex]

                                                           =  [tex]\frac{0.421}{244.26}[/tex]

                                                           = 0.017

Number of moles of 2Na₃PO₄ · 12 H₂O = [tex]\frac{\text{Mass of}\ Na_3PO_4. 12H_2O}{\text{Molar mass of}\ Na_3PO_4 . 12H_2O}[/tex]

                                                                 = [tex]\frac{0.722}{380.12}[/tex]

                                                                 = 0.002

Therefore, Na₃PO₄ · 12 H₂O is the limiting reagent.

Now, put the value in above formula to find the molarity

Molarity (M) = [tex]\frac{\text{number of moles}}{\text{volume of solution (in liters)}}[/tex]

                    = [tex]\frac{0.0017}{0.5}[/tex]

                    = 0.003 mol/L

Thus, from above conclusion we can say that 0.003 mol/L of Ba₃(PO4)₂ precipitate.

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Answer: The Answer would be C

Explanation: A spectrum is a Range of Wavelengths and Frequencies of Electromagnetic Radition.

The statement that describe spectrum is a range of wavelengths or frequencies of electromagnetic radiation.

Spectrum arrangement or electromagnetic radiations base on their wavelength and frequency which can be visible light, ultraviolet, and infrared light. An instrument that is use for visual observation of spectra is called a spectroscope.

Therefore, The statement that describe spectrum is a range of wavelengths or frequencies of electromagnetic

radiation.

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Answer: The volume of given container is 3.83 L.

Explanation:

Given: Mass of [tex]H_{2}[/tex] = 0.224 g

Mass of [tex]N_{2}[/tex] = 1.06 g

Mass of Ar = 0.834 g

Since, moles is the mass of a substance divided by its molar mass. Therefore, moles of given substances present in the mixture are as follows.

Moles of  [tex]H_{2}[/tex] are:

[tex]Moles = \frac{mass}{molar mass}\\= \frac{0.224 g}{2 g/mol}\\= 0.112 mol[/tex]

Moles of [tex]N_{2}[/tex] are:

[tex]Moles = \frac{mass}{molar mass}\\= \frac{1.06 g}{28 g/mol}\\= 0.038 mol[/tex]

Moles of Ar are:

[tex]Moles = \frac{mass}{molar mass}\\= \frac{0.834 g}{40 g/mol}\\= 0.021 mol[/tex]

Total moles = (0.112 + 0.038 + 0.021) mol = 0.171 mol

Now, using ideal gas equation the volume is calculated as follows.

PV = nRT

where,

P = pressure

V = volume

n = no. of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

[tex]V = \frac{nRT}{P}\\= \frac{0.171 mol \times 0.0821 L atm/mol K \times 273 K}{1 atm}\\= 3.83 L[/tex]

Thus, we can conclude that the volume of given container is 3.83 L.

Answer:

sodium fluoride

Explanation:

When we add sodium fluoride to a solution of a given mixture, we get barium fluoride from Ba, which would be an insoluble salt, and silver fluoride from Ag, which would be a soluble salt. 

The solubility rule will be used to determine the barium salt that forms as a precipitate and leaves Ag+ salt in the solution.

From the following equations, we will see that the precipitate is formed in Ba but Ag remains dissolved in the solution.

[tex]Ba(NO_3)_2{(aq)} + 2NaF_{(aq)} \to BaF_{2(s)} +2NaNo_{3(aq)}[/tex]

[tex]AgNo_{3(aq)} +NaF_{(aq)} \to AgF_{(aq)} + NaNO_{(aq)}[/tex]

Answer:

A molecule is the smallest particle of a substance that is made up of 2 or more atoms

An atom is the smallest particle of any pure element

An element is a substance that cannot be broken chemical and physical processes

A molecule is known as the building block of matter

A compound is a chemical substance that is made up of 2 more more different atoms bonded together

When the concentration of the HCl is varied, the color of the solution is changed as the equilibrium position moves to the left or right.

The term equilibrium in a chemical reaction connotes that the forward and the revers reactions proceed at the same rate. Let us note that Co(H2O)6^2+ is pink in color while  CoCl4^2– is blue in color.

As such, when the concentration of the HCl is varied, the color of the solution is changed as the equilibrium position moves to the left or right.

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Answer: Aluminum, because it allows heat to flow easily.

Have a nice day!

Answer:

si

Explanation:

Los catalizadores son sustancias que aceleran una reacción química, proporcionando una ruta alternativa para romper y formar nuevos enlaces entre átomos. Su importancia reside en el hecho de que este nuevo camino requiere menos energía que el original, lo que facilita el proceso.

Answer:

A. London dispersion

Explanation:

London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. 

The intermolecular forces are due to the attraction between temporary dipoles, and their induced temporary dipoles are the type of  London dispersion force. Therefore, option A is correct.

When the electrons in two nearby atoms occupy positions that cause the atoms to temporarily form dipoles, the consequence is the London dispersion force, a transient attractive force. The term "induced dipole-induced dipole attraction" is frequently used to describe this effect.

The electron density of a molecule is redistributed towards another molecule because the electrons in nearby molecules "flee" when they repel one another. This is typically explained as the instantaneous production of attracted dipoles.

The material's atomic or molecular weight affects the London dispersion forces. More electrons and stronger London forces are present in heavier atoms or molecules. They are therefore more difficult to melt or boil.

Thus, option A is correct.

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AAnswer:

Explanation:

Today, as part of the series of posts on soils, we are going to look at ‘soil texture’. Soil forms the basis for all life but it’s important to know about its mineral constitution as well as its biological profile.

Texture refers to the ‘feel’ of the soil. This is affected by the constituent materials found within it, specifically sand, silt and clay particles. A coarse sand will feel gritty but a wet clay will feel heavy and sticky. The texture of a soil has a direct impact on the way the soil reacts to certain environmental conditions – for example, towards drought or heavy rain (with sandy soils more freely draining).

There is a big difference in the size of the different particles.

Coarse sand = diameter 2-0.2mm

Fine sand = diameter 0.2-0.02mm

Silt = diameter 0.02-0.002mm

Clay = diameter less than 0.002mm

Note how the clay particles are much smaller than the sand particles – this is important as it means the total surface area of a clay soil is much greater and so the capacity to hold water is also much greater.

Between the sand, silt and clay particles there are lots of pores. In fact a soil as a whole is generally 45% mineral, 5% organic matter (depending on the soil) and 50% pore space through which air and water can pass.

Sand –

Made up of weathered primary rock minerals.

The particles are irregular in outline.

They are large and so do not pack together easily.

Large pore spaces in between.

Air gets in very easily and water flows rapidly through it.

Silt –

Answer:

[tex](24 \times 2) \: g \: of \: magnesium \: reacts \: with \: (16 \times 2) \: g \: of \: oxygen \\ 2.64 \: g \: of \: magnesium \: will \: react \: with \: ( \frac{2.64 \times 16 \times 2}{24 \times 2} ) \: g \\ = 1.76 \: g \: of \: oxygen[/tex]

Two airplanes are flying in the sky in such a way that the gravitational attractions between them decreases. The planes must be flying away from each other. Hence option A is correct.

Gravitational attraction is defined as a basic interaction that pulls everything with mass or energy in the same direction. All objects are subject to gravitational interactions, the strength of which is directly inversely proportional to the product of their masses. The size of an object and the separation between the objects have an impact on gravity.

In order to reduce the gravitational pull, two planes are flying in the sky. There must be a directionality between the aircraft. No matter what is in between the two bodies, there will still be gravitational pull. As a result, even if the medium between the two bodies changed, the gravitational force between them would not.

Thus, two airplanes are flying in the sky in such a way that the gravitational attractions between them decreases. The planes must be flying away from each other. Hence option A is correct.

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Explanation:

[tex] = 2.5\% \times 2000 \\ = \frac{2.5}{100} \times 2000 \\ = 50 \: g[/tex]

Answer:

Aspirin was purified in the lab by recrystallizing the crude aspirin. The melting point of the purified aspirin is expected to be lower than the melting point of crude aspirin.

Explanation:

The presence of impurities in a sample lowers the melting point of the impure substance. Hence the melting point of an impure substance is always less than the melting point of the corresponding pure substance.

Bearing this in mind, the statement "Aspirin was purified in the lab by recrystallizing the crude aspirin. The melting point of the purified aspirin is expected to be lower than the melting point of crude aspirin." is found to be false since impure substances tend to have a slightly lower melting point than the pure substance, and a broader melting temperature range.

Given :

A compound sodium trioxocarbonate (iv) decahydrate.

To Find :

The molecular mass of sodium trioxocarbonate (iv) decahydrate.

Solution :

We know, molecular formula of sodium trioxocarbonate (iv) decahydrate is :

Na₂CO₃.10H₂O

Now, we can calculate its molecular mass :

M = ( 2 × 23 ) + 12 + ( 3 × 16 ) + 10 × ( 1 × 2 + 16)

M = 46 + 12 + 48 + ( 10 × 18 )

M = 286 gram/mol

Hence, this is the required solution.

Answer:

1.61

Explanation:

Answer: A Molecular Approach, 2/e. Mole ratio. 2 mol C4H10 : 13 mol O2 : 8 mol CO2 : 10 mol H2O. ❖ 2 molecules of C4H10 react ... of aluminum and 73.15 g of sulfur are combined to form aluminum sulfide according to the equation:.

Explanation:

Answer: The half-reactions represents reduction are as follows.

Explanation:

A half-reaction where addition of electrons take place or a reaction where decrease in oxidation state of an element  takes place is called reduction-half reaction.

For example, the oxidation state of Cr in [tex]Cr_{2}O^{2-}_{7}[/tex] is +6 which is getting converted into +3, that is, decrease in oxidation state is taking place as follows.

[tex]Cr_{2}O^{2-}_{7} + 3 e^{-} \rightarrow Cr^{3+}[/tex]

Similarly, oxidation state of Mn in [tex]MnO^{-}_{4}[/tex] is +7 which is getting converted into +2, that is, decrease in oxidation state is taking place as follows.

[tex]MnO^{2-}_{4} + 5 e^{-} \rightarrow Mn^{2+}[/tex]

Thus, we can conclude that half-reactions represents reduction are as follows.

Answer:

Baking Soda is NaHCO3 ---Sodium hydrogen Carbonate

Excessive use of Fertilizer can cause plants to develop shallow root systems,Decrease soil fertility and reduce Quality of Crops.

Answer:

Sodium bicarbonate, also called sodium hydrogen carbonate, or bicarbonate of soda,  is a source of carbon dioxide and so is used as an ingredient in baking powders, in effervescent salts and beverages, and as the main constituent of dry-chemical fire extinguishers.

Explanation:

Answer:

The answer is "the electron configuration of the element".

Explanation:

Electronics are distributed in atomic and molecular orbit via electrons from an atom or a molecule.

It reflects a most frequent dependence on valence electrons in the outer.

Through analyzing the context of the regular periodic table, the individual atoms are helpful. That's also important to understand chemical connections, which hold electrons together. This similar approach helps to explain the specific characteristics of lasers or semiconductors for bulk materials.

Answer:

1/3 dilution : 1 volume of stock solution + 2 volumes of diluent

Explanation:

Concentrated solution = 0.300 NaOH

Diluted solution = 0.100 NaOH

The dilution factor is : 0.100/0.300 = 1/3

Thus, we have to dilute three times the stock solution. For this, we take 1 volume of stock solution and then we add 2 volumes of diluent. As result, we will have 1 volume of stock solution in a total of 3 volumes. For example, we take 1 mL of 0.300 NaOH and then we add 2 mL of diluent (0.300 NaCl). The final concentration after dilution will be:

Cd = 0.300 M x 1 mL/3 mL = 0.100 M