______ is required for making a scientific inquiry

Joseph Priestly is frequently credited with the discovery of oxygen, and was reported to have produced molecular oxygen from the decomposition reaction of mercury(II) oxide, which is the reverse of the synthesis of HgO depicted in the following equation. [tex]4Hg(l)+2O_2(g)\rightarrow 4 HgO(s) [/tex]Determine the value of [tex]\Delta ΔH°rxn[/tex] for the synthesis, given that [tex]\Delta H_f^0[/tex] for HgO is -90.7 kJ/mol.

Answer: The enthalpy change for this reaction is, -362.8 kJ

Explanation:

The balanced chemical reaction is,

[tex]4Hg(l)+2O_2(g)\rightarrow 4HgO(s)[/tex]

The expression for enthalpy change is,

[tex]\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)][/tex]

[tex]\Delta H=[(n_{HgO}\times \Delta H_{HgO})]-[(n_{O_2}\times \Delta H_{O_2})+(n_{Hg}\times \Delta H_{Hg})][/tex]

where,

n = number of moles

[tex]\Delta H_{O_2}=0[/tex] (as heat of formation of substances in their standard state is zero

[tex]\Delta H_{Hg}=0[/tex] (as heat of formation of substances in their standard state is zero

Now put all the given values in this expression, we get

[tex]\Delta H=[(4\times -90.7)]-[(2\times 0)+(4\times 0)][/tex]

[tex]\Delta H=-362.8kJ[/tex]

Therefore, the enthalpy change for this reaction is, -362.8 kJ

Answer:

1. 0.74mol

2. 0.42mol

3. 2.125mol

4. 0.301mol

5. 4.52 × 10^23 particles

Explanation:

Number of moles (n) in a substance can be found using the formula:

mole (n) = mass/molar mass

Using this formula, the following moles are calculated:

1. Molar of Na = 23g/mol

mole = 17/23

mole = 0.74mol

2. Molar mass of Na2SO4 = 23(2) + 32 + 16(4)

= 46 + 32 + 64

= 142g/mol

Mole = 60/142

mole = 0.42mol

3. Molar mass of CO2 = 12 + 16(2)

= 12 + 32

= 44g/mol

mole = 93.5/44

mole = 2.125mol

4. Molar mass of sodium nitrate (NaNO3) = 23 + 14 + 16(3)

= 23 + 14 + 48

= 85g/mol

mole = 25.6/85

mole = 0.301mol

5. Number of particles in one mole of a substance is 6.022 × 10^23 particles. Hence, in 0.75mol of calcium hydroxide (Ca(OH)2, there will be;

0.75mol × 6.02 × 10^23

= 4.515 × 10^23

= 4.52 × 10^23 particles

Answer: The empirical formula is [tex]C_3H_3O[/tex].

Explanation:

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

[tex]C_xH_yO_z+O_2\rightarrow CO_2+H_2O[/tex]

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of [tex]CO_2[/tex] = 12.24 g

Mass of [tex]H_2O[/tex] = 2.505 g

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 12.24 g of carbon dioxide, =[tex]\frac{12}{44}\times 12.24=3.338g[/tex] of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 2.505 g of water, =[tex]\frac{2}{18}\times 2.505=0.278g[/tex] of hydrogen will be contained.

Mass of oxygen in the compound = (5.287) - (3.338+0.278) = 1.671  g

Step 1 : convert given masses into moles.

Moles of C =[tex] \frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{3.338g}{12g/mole}=0.278moles[/tex]

Moles of H=[tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.278g}{1g/mole}=0.278moles[/tex]

Moles of O=[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{1.671g}{16g/mole}=0.104moles[/tex]

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C =[tex]\frac{0.278}{0.104}=3[/tex]

For H =[tex]\frac{0.278}{0.104}=3[/tex]

For O =[tex]\frac{0.104}{0.104}=1[/tex]

The ratio of C : H : O = 3: 3: 1

Hence the empirical formula is [tex]C_3H_3O[/tex].

The empirical formula : C. C₁₆H₁₅N₂

Given

12.5 g of aniline

7.1 grams of H2O

1.48 grams of N2

Required

The empirical formula

Solution

Reaction :

mass H in H₂O :

= 2.1/18 x 7.1 g

= 0.79

mass N = 1.48

mass C :

= 12.5 g-(mass H+mass N)

= 12.5 - (0.79+1.48)

= 10.23

Mol ratio C : H : N =

= 10.23/12 : 0.79/1 : 1.48/14

= 0.853 : 0.79 : 0.106

= 8 : 7.5 : 1

= 16 : 15 : 2

Answer: electrons

Explanation:

Answer: It is called an electron because it is attracted to the positively charged particales called protons in the center of the atom.

Explanation:

Answer:

Activation energy for the uncatalyzed reverse reaction = 103 kJ/mol

Explanation:

Activation energy decreases from = 56 kj/mol to 35 kj/mol

products = 78 KJ lower in energy than reactants

Activation energy for the uncatalyzed reverse reaction = 103 kJ/mol

attached below are the sketches of approximate energy-level for both catalyzed and uncatalyzed reactions

Answer:

42.658

Explanation:

1) Avogadro's number is: N(A)=6.02*10²³

2) M of (Mo₂(SO₄)₃)=96*2+96*3=480 (gr/mol);

3) if N(A) ~ 1 mol of (Mo₂(SO₄)₃), tnen 5.35*10²² ~

(5.35*10²²)/(6.02*10²³)≈0.0888 mol of (Mo₂(SO₄)₃);

4) m(Mo₂(SO₄)₃)=M(Mo₂(SO₄)₃)*0.0888;

m((Mo₂(SO₄)₃)=480*0.0888=42.658 (gr)

Answer:

thermal conductors

steel

polystyrene

thermal insulator

between things of the same temp?

sorry to ask but if its ok with you, may i get brainly, i need to rank up all i need is two more, if not its fine. thank you and yours truly golden

Answer:

Explanation:

Bromine >Tellurium > Phosphorus > Helium > Sodium

Electron affinity of Bromine , Tellurium , Phosphorus are positive , of helium is zero and of sodium is negative .

Answer:

points

Explanation:

Answer:

Where is the diagram?

Explanation:

..........................

Answer:

1.2 cm

Explanation:

The reason how I got my answer is by dividing 150 by 125 and that gave me 1.2 cm.

Answer:

See explanation below

Explanation:

First, let's write the reaction:

NH₄SH(s)   <------> H₂S(g) + NH₃(g)

The reaction is already balanced so we don't need to do anything else.

Second, let's take into account the following. The Kc expression for this reaction, only compounds in gaseous state are the only ones that contribute to the equilibrium. Solid and liquid do not contribute to the Kc expression. This is because solid and liquid have a constant concentration near to 1, so, it won't do any difference.

Knowing this, the Kc expression for this reaction is:

Kc = [H₂S] [NH₃]

Now, to calculate Kp from Kc, there's an expression that helps a lot to do this. The expression is the following:

Kp = Kc (RT)ᵃⁿ    (1)

Where:

R: universal constant of gases

T: Temperature in K

ᵃⁿ = difference of the coefficients of the reaction.

This expression comes from the fact that Kp is an expression that instead of working with concentrations, it works with pressure.

If we use the ideal gas equation we have:

PV = nRT

Solving for P:

P = nRT/V        and C = n/V   so

P = CRT

If we now replace this, in the Kp expression of equilibrium we have:

Kp = pH₂S * pNH₃

Kp = ([H₂S]RT)¹ ([NH₃]RT)¹

Kp = (RT)¹⁺¹ ([H₂S] [NH₃])

Kp = (RT)²Kc

So finally the expression for Kp would be:

Hope this helps

Answer:

See explanation below

Explanation:

You are not providing the starting material, however, I manage to find a similar question to this, so I'm gonna use it as a basis to help you answer yours.

Now let's analyze what is happening in the reaction so we can predict the final product.

We have a ketone here, reacting at first with LDA. This is a very strong base that is commonly used in reactions with ketones and aldehydes to promove a condensation. To do this, as LDA is a strong base it will occur firts an acid base reaction, substracting the most acidic hydrogen in the molecule (Which in this case, is the Beta hydrogen of the carbonile). This will cause an enolate formation.

Then, this enolate will react with the CH3I and form a new product. The final result would be a ketone with a methyl group now attached. In the picture 2, you have the mechanism and final product.

Hope this helps

Answer:

See explanation and images attached

Explanation:

a) In the mechanism for the acid catalysed esterification of propanoic acid using ethanol, we can see that the first step is the protonation of the acid followed by nucleophillic attack of the alcohol. Loss of water and consequent deprotonation regenerates the acid catalyst. We can see the fate of the 18O labelled ethanol in the mechanism shown.

b)  In the second mechanism, an unnamed ester is hydrolysed using an acid catalyst. The attack of the acid and subsequent nucleophillic attack of water labelled with 18O leads to the incorporation of this 18O into the product acid as shown in the mechanism attached to this answer.

Answer:

3.2 × 10³ J

Explanation:

Step 1: Given data

Step 2: Calculate the temperature change (ΔT)

ΔT = 1064 °C - 75 °C = 989 °C

Step 3: Calculate the energy required (Q)

We will use the following expression.

Q = Cp × m × ΔT

Q = 0.129 J/g.°C × 25 g × 989 °C

Q = 3.2 × 10³ J

Answer:

[tex]d=7.77\times 10^{13}\ m[/tex]

Explanation:

We know that the speed of light is equal to [tex]3\times 10^8\ m/s[/tex]

We need to find how far the light travel in 3 days.

Speed of an object is equal to distance covered divided by time taken.

Also, 1 day = 86400 s

3 days = 259200 s

So,

[tex]d=vt[/tex]

[tex]d=3\times 10^8\times 259200\\\\d=7.77\times 10^{13}\ m[/tex]

So, the light will travel [tex]7.77\times 10^{13}\ m[/tex] in 3 days.

Answer:

Explanation:

if it has a lower density than the liquid it's in will float

Answer:

b

Explanation:

it is not c because water expands when it freezes.

Answer:

hello your question is incomplete attached below is the complete question

answer :

Absence of c = c = C-H of the peak and the presence of -O-H and C-O peak shows that there is presence of Alcohols as products and it also shows that there is no starting material left

Explanation:

To provide that there is no starting material left and products are alcohols using the IR spectrum we will apply hydroboration oxidation

Absence of c = c = C-H of the peak and the presence of -O-H and C-O peak shows that there is presence of Alcohols as products and it also shows that there is no starting material left

attached below is the detailed solution

Answer:

The mass in grams of N₂O gas that can be dissolved is 0.18 g

Explanation:

The solubility of a gas is proportional to the partial pressure of that gas, over a determined solvent. That's what Henry's law states. We see the formula:

S = K . Pp

Where S is solubility and K is Henry's constant. This specific for each gas and each temperature, while Pp means partial pressure.

We replace data:

S = 0.025 M/atm .  0.69atm

S = 0.01725 M

This is the solubility of the gas, so now, we need to know what mass of gas is solubilized. We convert the moles, with the volume of water.

0.01725 mol/L . 0.235 L = 4.05×10⁻³ moles

Now, we determine the mass in grams:  4.05×10⁻³ mol . 28 g / 1mol =

0.1782 g

Answer:

Explanation:

molecular weight of NO₂ is 14 + 2 x 16 = 46

So one mole of nitrogen dioxide will have mass of 46 grams .

Answer: 1.2 x 10^-17 microounces

Explanation:

Ounce = 28.5G microounce = 28.5*10^-6g

3.4*10^-25 kg = 3.4*10^-22 g = (3.4/2.85)*10^(-22+5) = 1.2*10-17

Answer:

2

Explanation:

Based on the chemical equation, the number of molecules of hydrogen gas in the reactant side is 2.

This is indicated by the coefficient before reactant.

A molecule is a covalent compound that has discrete or separate units.

So H₂ is made up of two atoms of hydrogen that has been covalently bonded together by sharing their valence electrons.

From the reaction expression:

   2 molecules of hydrogen gas combines with 1 molecule of oxygen gas to produce 2 molecules of water.

An SDOF system is one whose motion is governed by a single, second-order differential equation. Only two variables, position and velocity are needed to describe the trajectory of the system. Many structures can be idealized as single degree-of-freedom systems.

The LDAP Data Interchange Format is a standard plain text data interchange format for representing LDAP directory content and update requests. LDIF conveys directory content as a set of records, one record for each object.

Answer:

O Each orbit has a specific energy level.

Explanation:

Neils Bohr put forward his own model of the atom based on the quantum mechanics originally developed by Planck.

He assumed the Rutherford's model and suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus.

The orbits/energy level are the permissible through which the electrons can move through.

His concept is based the concept that the electron can move round the nucleus in certain permissible orbitss

Answer:

0.0847M is molarity of sodium hydrogen citrate in the solution

Explanation:

The 2.0%(w/v) solution of sodium hydrogen citrate contains 2g of the solute in 100mL of solution. To find the molarity of the solution we need to convert the mass of solute to moles using molar mass and the mL of solution to Liters because molarity is the ratio between moles of sodium hydrogen citrate and liters of solution.

Moles Na2C6H6O7:

Molar Mass:

2Na: 2*22.99g/mol: 45.98g/mol

6C: 6*12.01g/mol: 72.01g/mol

6H: 6*1.008g/mol: 6.048g/mol

7O: 7*16g/mol: 112g/mol

45.98g/mol + 72.01g/mol + 6.048g/mol + 112g/mol = 236.038g/mol

Moles of 2g:

2g * (1mol / 236.038g) = 8.473x10⁻³ moles

Liters solution:

100mL * (1L / 1000mL) = 0.100L

Molarity:

8.473x10⁻³ moles / 0.100L =

Answer:

0.085M

Explanation:

Molecular weight of sodium hydrogen citrate=236.09 g

236.09 g of Na2C6H6O7 in 1000ml= 1 M

2%= 2 g in 1 litre (1000ml)

20/236.09=0.0847 M=0.085 M

Answer:

Unlike a permanent magnet, an electromagnet can be turned on and off using electrical current. Many variables affect the strength of this electromagnet, and there are some variables that do not affect the strength. ... Making the nail longer will not make the magnet stronger, unless you also add more turns to the coil.

electromagnet can be turned on and off using electrical current. Many variables affect the strength of this electromagnet, and there are some variables that do not affect the strength

Answer:

C. P = nRT

Explanation:

PV = nRT, where n is a number of moles and R is the universal gas constant, R = 8.31 J/mol ⋅ K.

Hope this helps :)

Answer:T =PV/nR

Explanation: