which two options are examples of chemical changes?
A. A shinny metal bar glows red and expands when heated.

B. white piece of paper turns black and gives off a smell when burned

C. When two clear colorless liquids are mixed together, a white solid forms

D. A white powder mixed with a clear, colorless liquid makes a solution that is also clear, colorless liquid

Answers

Answer 1

Answer:

B

Explanation:

It's the only thing that actually changes into something different and when u burn it it makes chemicals


Related Questions

When 60 mL of 0.22 M NH4Cl is added to 60 mL of 0.22 M NH3, relative to the pH of the 0.10 M NH3 solution the pH of the resulting solution will:____________.

Answers

Answer:

Will be more acidic

Explanation:

The equilibrium of NH3 in water is:

NH3(aq) + H2O(l) ⇄ NH4⁺(aq) + OH⁻(aq).

Where equilibrium constant, Kb, is:

Kb = 1.85x10⁻⁵ = [NH4⁺] [OH⁻] / [NH3]

From 0.10M NH3, the reaction will produce X of NH4⁺ and X of OH⁻ and Kb will be:

1.85x10⁻⁵ = [X] [X] / [0.10M]

1.8x10⁻⁶ = X²

X = 1.34x10⁻³ = [OH⁻]

As pOH = -log[OH⁻] = 2.87

And as pH = 14 - pOH

pH of the 0.10M NH3 is 11.13

Now, to find the pH of the NH4Cl and NH3 we need to use H-H equation for bases:

pOH = pKb + log [NH4⁺] / [NH3]

Where pKb is -log Kb = 4.74 and [] are moles of both compounds.

Moles of [NH4⁺] = [NH3] = 60mL, 0.060L*0.22M = 0.0132moles:

pOH = 4.74 + log [0.0132] / [0.0132]

pOH = 4.74

pH = 14 - 4.74 = 9.26

That means the pH of the resulting solution will be more acidic

A certain first-order reaction has a rate constant of 2.10×10−2 s−1 at 19 ∘C. What is the value of k at 58 ∘C if Ea = 82.0 kJ/mol ?

Answers

Answer:

K₂ = 1.12s⁻¹

Explanation:

Based on Arrhenius equation:

ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)

Where K is rate constant,

R is gas constant (8.314J/molK),

T is absolute temperature (In K) Of 1, initial state and 2, final state.

ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)

ln K₂/2.10x10⁻²s⁻¹ = -82000J/mol/8.314J/molK (1/(273.15 + 58) - 1/(273.15 + 19))

ln K₂ / 2.10x10⁻²s⁻¹ = 3.976

K₂ / 2.10x10⁻²s⁻¹ = 53.3

K₂ = 1.12s⁻¹

For which of the following processes would S° be expected to be most positive? a) O2(g) + 2H2(g)  2H2O(g) b) H2O(l)  H2O(s) c) NH3(g) + HCl(g)  NH4Cl(g) d) 2NH4NO3(s)  2N2(g) + O2(g) + 4H2O(g) e) N2O4(g)  2NO2(g) 12. Which of the following statements is

Answers

Answer:

Explanation:

a) O₂(g) + 2H₂(g) = 2H₂O

b) H₂O(l) = H₂O(s)

c) NH₃(g) + HCl(g) =  NH₄Cl(g)

d) 2NH₄NO₃(s) =  2N₂(g) + O₂(g) + 4H₂O(g)

e) N₂O₄(g) =  2NO₂(g)

ΔS is positive when there is increase in disorderliness. It happens when there is increase in volume .

Increase is volume is maximus in the following reaction.

d) 2NH₄NO₃(s) =  2N₂(g) + O₂(g) + 4H₂O(g)

in this reaction solid NH₄NO₃ is changed to 7 x 22.4 L of gases so there is maximum increase in volume . Hence maximum increase in entropy . Hence ΔS is most positive .

the mass number of Fe is 56 . how many neutron are there in a single Fe atom

Answers

Answer:

30 neutrons

Explanation:

Since the mass of the iron nuclide is 56 , there must be 56−26=30 neutrons, 30 massive, neutral particles in this iron nucleus.

Aluminum metal and bromine liquid (red) react violently to make aluminum bromide (white powder). One way to represent this equilibrium is:
Al(s) + 3/2 Br2(l)AlBr3(s)
We could also write this reaction three other ways, listed below. The equilibrium constants for all of the reactions are related. Write the equilibrium constant for each new reaction in terms of K, the equilibrium constant for the reaction above.
1) 2 AlBr3(s) 2 Al(s) + 3 Br2(l)
2) 2 Al(s) + 3 Br2(l) 2 AlBr3(s)
3) AlBr3(s) Al(s) + 3/2 Br2(l)

Answers

Answer:

Explanation:

Al(s) + 3/2 Br₂(l) = AlBr₃(s)

K = [  AlBr₃] / [ Al] [  Br₂]³/²

K² =  [  AlBr₃]² / [  Al ] ² [ Br₂]³

2 AlBr₃ = 2 Al(s) + 3 Br₂(l) =

K₁ =  [  Al ] ² [ Br₂]³ /  [  AlBr₃]²

K₁ =  ( 1 / K² ) = K⁻²

2 ) 2 Al(s) + 3 Br₂(l) = 2 AlBr₃(s)

K₂ = [ AlBr₃ ]² / [  Al ]² [  Br₂ ]³

K₂ = K²

3 )

AlBr₃(s) =   Al(s) + 3/2 Br₂(l)

K₃  = [ Al ] [ Br₂ ] ³/² / [ AlBr₃ ]

=  ( 1 / K ) = K⁻¹

Why doesn't chromic acid oxidize tertiary alcohol?​

Answers

Tertiary alcohols don't have a hydrogen atom attached to that carbon. You need to be able to remove those two particular hydrogen atoms in order to set up the carbon-oxygen double bond. Well I checked that on Google, hope I helped you.

BaCl2+Na3PO4-->NaCl+Ba3 (PO4)2If 3.54g of Ba3 (PO4)2are produce by the reaction given how many grams of the starting material BCl2 were used?a) 3.680 gb) 1.23 gc) 3.68 gd) 4.16 g

Answers

Answer:

1.23 g

Explanation:

Given that the mass of barium phosphate formed= 3.54 g

Molar mass of Ba3 (PO4)2 = 602 g/moles

Number of moles of Ba3 (PO4)2= 3.54g/602 g/moles = 0.0059 moles

Since 1 mole of BaCl2 forms 1 mole of Ba3 (PO4)2

Hence, 0.0059 moles of BaCl2 yields 0.0059 moles of Ba3 (PO4)2

Hence mass of BaCl2 reacted= mass × molar mass= 1.23 g

A mixture of cyclopropane gas and oxygen is used as an anesthetic. Cyclopropane contains 85.7% C And 14.3% hydrogen by mass. At 50.0 degrees celcius and .984 atm pressure, 1.56 g cyclopropane has a volume of 1.00L.

Required:
What is the molecular formula of cyclopropane?

Answers

Answer:

C₃H₆

Explanation:

We'll begin by calculating the empirical formula for cyclopropane. This is illustrated below:

Carbon (C) = 85.7%

Hydrogen (H) = 14.3%

Divide by their molar mass

C = 85.7/12 = 7.14

H = 14.3/1 = 14.3

Divide by the smallest:

C = 7.14/7.14 = 1

H = 14.3/7.14 = 2

Therefore, the empirical formula for the cyclopropane is CH₂

Next, we shall determine the number of mole of cyclopropane.

This can be obtained as follow:

Temperature (T) = 50 °C = 50 °C + 273 = 323 K

Pressure (P) = 0.984 atm

Volume (V) = 1 L

Gas constant (R) = 0.0821 atm.L/Kmol

Number of mole (n) of cyclopropane =.?

PV = nRT

0.984 × 1 = n × 0.0821 × 323

Divide both side by 0.0821 × 323

n = 0.984 / (0.0821 × 323)

n = 0.0371 mole

Next, we shall determine the molar mass of cyclopropane. This can be obtained as follow:

Number of mole of cyclopropane = 0.0371 mole

Mass of cyclopropane = 1.56 g

Molar mass of cyclopropane =.?

Mole = mass /Molar mass

0.0371 = 1.56/Molar mass

Cross multiply

0.0371 × Molar mass = 1.56

Divide both side by 0.0371

Molar mass = 1.56 /0.0371

Molar mass of cyclopropane = 42.05 g/mol.

Finally, we shall determine the molecular formula for cyclopropane. This can be obtained as follow:

[CH₂]ₙ = 42.05

[12 + (2×1)]ₙ = 42.05

[12 + 2]ₙ = 42.05

14n = 42.05

Divide both side by 14

n = 42.05/ 14

n = 3

Thus,

[CH₂]ₙ => [CH₂]₃ => C₃H₆

Therefore, the molecular formula for cyclopropane is C₃H₆

The molecular formula of cyclopropane ([tex]CH_2[/tex]) is equal to [tex]C_3H_6[/tex]

Given the following data:

Percent mass of cyclopropane = 85.7%Percent mass of hydrogen = 14.3%Temperature = 50.0°C to Kelvin = [tex]273+50=323\;K[/tex]Pressure = 0.984 atm.Mass of cyclopropane = 1.56 grams.Volume of cyclopropane = 1.00 Liter.

Scientific data:

Ideal gas constant, R = 0.0821L⋅atm/mol⋅KThe atomic weight of carbon (C) = 12 g/molThe atomic weight of hydrogen (H) = 1 g/mol

To determine the molecular formula of cyclopropane:

First of all, we would determine the molar mass and number of moles of cyclopropane by using the ideal gas law equation;

[tex]PV=\frac{M}{MM} RT[/tex]

Where;

P is the pressure.V is the volume.M is the mass of gas.MM is the molar mass of gas.R is the ideal gas constant.T is the temperature.

Making MM the subject of formula, we have:

[tex]MM = \frac{MRT}{PV} \\\\MM = \frac{1.56\;\times \;0.0821\times \;323}{0.984\;\times \;1}\\\\MM = \frac{41.3686}{0.984}[/tex]

Molar mass, MM = 42.04 g/mol.

For number of moles:

[tex]Number\;of\;moles = \frac{mass}{molar\;mass}\\\\Number\;of\;moles = \frac{1.56}{42.04}[/tex]

Number of moles = 0.0371 moles

Next, we would determine the empirical formula of cyclopropane:

For carbon (C):

[tex]C = \frac{85.7}{12}[/tex]

Carbon (C) = 7.1417

For hydrogen (H):

[tex]H = \frac{14.3}{1}[/tex]

Hydrogen (H) = 14.3

Simplest whole number ratio:

[tex]C = \frac{7.1417 }{7.1417 } =1[/tex]

[tex]H= \frac{14.3 }{7.1417 } =2[/tex]

Empirical formula of cyclopropane = [tex]CH_2[/tex]

Now, we can determine the molecular formula of cyclopropane:

[tex](CH_2)n = 42.04\\\\(12 + 1\times2)n=42.04\\\\14n=42.04\\\\n=\frac{42.04}{14}[/tex]

n = 3

Molecular formula of cyclopropane ([tex]CH_2[/tex]) = [tex](CH_2)_3 =C_3H_6[/tex]

Read more: https://brainly.com/question/21280037

State the number of sig figs in each value:


1) 0.00004050

2) 54.7000

3) 1,000.09

4) 0.039

Answers

Answer:

Explanation:

Significant figure implies number of digits that are to be considered. Some rules are required to be considered when writing a given expression to an expected significant figures.

So that:

1) 0.00004050 is 4 significant figures

2) 54.7000 is 6 significant figures

3) 1,000.09 is 6 significant figures

4) 0.039 is 2 significant figures

A geochemist has determined by measurements that there are moles of tin in a sample of cassiterite. How many moles of oxygen are in the sample

Answers

The question is incomplete, the complete question is:

This is the chemical formula for cassiterite (tin ore): SnO2 A geochemist has determined by measurements that there are 13. moles of tin in a sample of cassiterite. How many moles of oxygen are in the sample? Round your answer to 2 significant digits.

Answer:

Explanation:

In SnO2, there are two moles of oxygen for each mole of tin.

Hence, if there are 13 moles of tin, then we should have 13 * 2 moles of oxygen. This gives us 26 moles of oxygen.

Hence there are 26 moles of oxygen.

Calculate the wavelength of light (in nm) of the spectral line of Hydrogen where an electron falls from the 6th Bohr orbit to the 3rd Bohr orbit.

a) 540 nm
b) 2000 nm
c) 1090 nm
d) 1050 nm

Answers

Answer:

The wavelength of light (in nm) of the spectral line of Hydrogen where an electron falls from the 6th Bohr orbit to the 3rd Bohr orbit is 1090nm

Explanation:

We know that , the wavelength of the light is calculated by Rydberg's formula-

[tex]\frac{1}{\pi} =R^2(\frac{1}{n^2_1} -\frac{1}{n^2_2})[/tex]  [tex][n_2>n_1][/tex]

Here , R = Rydberg's constant [tex](1.097\times 10^7 m^-^1)[/tex]

          Z = atomic number (for hydrogen , Z= 1)

     [tex]n_2 =6 , n_1=3[/tex]

[tex]\pi =[/tex] wavelength of light

Now , putting the values in the Rydberg's formula ,

  [tex]\frac{1}{\pi} =1.097\times10^7m^-^1(\frac{1}{3^2} -\frac{1}{6^2} )[/tex]

     =[tex]1.097\times 10^7m^-^1 (\frac{4-1}{36} )[/tex]

    =[tex]1.097\times 10^7m^-^1(\frac{3}{36} )[/tex]

      =[tex]1.097\times 10^7m^-^1(\frac{1}{12} )[/tex]

  [tex]\frac{1}{\pi}[/tex]   = [tex]0.0914167\times 10^7m^-^1[/tex]

[tex]\pi=\frac{1}{0.0914167\times10^7m^-^1}[/tex]

[tex]\pi=10.9389\times10^-^7\\\pi=1093.89\times10^-^9m[/tex]

  =1090nm

Hence , the wavelength of the light is 1090nm,, that is option D is correct.

3. A certain Chemical Industry company has a quality control job opening. The job is open for any major with basic knowledge of chemistry. You decided to apply. In the interview the HR personnel gives you a sealed folder from a certain lot to test your laboratory experience, as well as your quantitative and volumetric analysis skills. The chemical contained in the sample is benzoic acid (C-H602) and it is known to be a monoprotic acid. In order to get the job, you need to determine if the sample's purity is acceptable based on their standards. Inside the folder you found a vial with a solid sample labeled BA-I, a periodic table, and the following data: 1.250 g of the sample required 20.15 mL of 0.500 M concentration of NaOH to reach the end point. The lot can be denied if the purity is below 99.5 % purity.

1) What is the purity in the sample?
2) Is it the purity acceptable?
3) Would you repeat the titration experiment?​

Answers

Answer:

1) 97.6%

2) No the purity is not acceptable because the standard is 99.5% purity.

3) Yes I will repeat the titration experiment to confirm my result.

Explanation:

Equation of the reaction;

C7H6O2(aq) + NaOH(aq) ---------> C7H5ONa(aq) + H2O(aq)

From the information provided;

Number of moles of NaOH reacted = concentration × volume = 20.15/1000 × 0.500 = 0.01 moles

From the reaction equation;

1 mole of C7H6O2 reacts with 1 mole of NaOH

Hence 0.01 moles of C7H6O2 will react with 0.01 moles of NaOH

Mass of C7H6O2 reacted = number of moles of C7H6O2 × molar mass of C7H6O2

Molar mass of C7H6O2 = 122.12 g/mol

Mass of C7H6O2 reacted = 0.01 moles × 122.12 g/mol = 1.22 g

Percentage by mass of pure C7H6O2 in the impure sample = 1.22/1.250 × 100 = 97.6 %

Which of the following is one way creativity can help scientists?

By ensuring they follow the scientific method
By increasing the amount of time it takes to complete scientific experiments
By making sure they only try things that have already been proven
By leading them to ask more questions about the natural world

Answers

Answer:

Creativity can help scientists by leading them to ask more questions about the natural world.

Explanation:

Beacause they use creativity to make up questions about the natural world.


Which are characteristics of all living things?

Answers

Order, sensitivity or response to the environment, reproduction, growth and development, regulation, homeostasis, and energy processing.

What is the best way to organize desert several several million different types of organisms on earth

Answers

Answer:

The desert should be divided into different types based on its properties. The organisms living in specific type of desert should be named accordingly.

Explanation:

There are usually five major types of desert in the world. Tropical, rainy, semi arid desert, coastal desert and dry desert. There are many different types of organisms living in these deserts. The biodiversity has made it difficult for the humans to analyse and identify the millions of different types. The best way is to organize and name the organisms that live in specific types of deserts.

All organelles that only plant cells have

Answers

Answer:

Cell wall, chloroplast, and vacuoles

Explanation:

What is the amount of charge on a calcium ion if its neutral atom has lost two valence electrons?
A. 1+
B. 2+
C. 3+
D. 4+

Answers

Answer: B

Explanation: a calcium ion has a charge of +2 because it has 2 more protons than electrons giving it a positive charge instead of neutral or negative.

Option B
Hope it will help you

Suppose the reaction Ca3(PO4)2 + 3H2SO4 → 3CaSO4 + 2H3PO4 is carried out starting with 149 g of Ca3(PO4)2 and 86.9 g of H2SO4. How much phosphoric acid will be produced?

Answers

Answer:

57.9 grams .

Explanation:

Ca₃(PO₄)₂ + 3H₂SO₄   → 3CaSO₄ + 2H₃PO₄

1 mole         3 moles                              2 moles

149 g of Ca₃(PO₄)₂ = 149 / 310 = .48 moles

86.9 g of H₂SO₄ = 86.9 / 98 = .8867 moles

Here H₂SO₄  is the limiting reagent .

.8867 / 3 = .2955

.2955 moles of Ca₃(PO₄)₂ reacts with  .8867 mole of H₂SO₄  to give

2 x .2955 moles of H₃PO₄

H₃PO₄ produced = 2 x .2955 moles

= .591 moles

= .591 x 98 = 57.9 grams .

The three dots in the Lewis dot diagram for boron indicates that it. Please help

Answers

Answer:

valence electrons

Explanation:

it is outermost shell of electrons

The three dots in the Lewis dot diagram for boron indicates that it has three valence electrons.

The three dots in the Lewis dot diagram for boron indicates that it

can bond with three other atoms. NO. It can bond with less than 3 atoms by forming double or triple bonds.can only form triple covalent bonds. NO. It can also form single and double covalent bonds.has three valence electrons. YES. It has 3 electrons in the outermost electron shell.scores a 3 on Pauling's electronegativity scale. NO. The electronegativity of boron is 2.04.

The three dots in the Lewis dot diagram for boron indicates that it has three valence electrons.

You can learn more about the Lewis dot structure here: https://brainly.com/question/20300458

Which are replenished MORE quickly than they are used?
A. energy resources

B. material resources
C. renewable resources
D. nonrenewable resources

Answers

Answer:c

Explanation: more expensive so people use nonrenewed energy more.

Identify the following reaction as an endothermic reaction, exothermic reaction, or both endothermic and exothermic:

Dissolving NH4Cl in water to make a cold pack.

Answers

Answer:

Endothermic reaction

Explanation:

Endothermic reactions are defined as the type of chemical reaction in which the system absorbs the energy from the surroundings and the temperature of the surrounding decreases while in Exothermic reactions, heat is released by the system to the surroundings and it makes the surrounding warm.

The given example is an "endothermic reaction" because the reaction between NH4Cl and water is making the surrounding cool (cold pack) due to the release of heat.

Hence, the correct answer is "endothermic reaction".

Aspirin is a weak organic acid whose molecular formula is HC9H7O4. An aqueous solution of aspirin is prepared by dissolving 3.60 g/L. The pH of this solution is found to be 2.6. Calculate Ka for aspirin. (atomic mass: C

Answers

Answer:

Ka = 3.50x10⁻⁴

Explanation:

First, we need to convert the unit of 3.60 g/L to mol/L:

[tex] C_{C_{9}H_{8}O_{4}} = 3.60 \frac{g}{L}*\frac{1 mol}{180.16 g} = 0.0200 mol/L [/tex]

The reaction dissociation of aspirin in water is:

C₉H₈O₄  +  H₂O  ⇄  C₉H₇O₄⁻ + H₃O⁺    

0.02 - x                        x             x

The constant of the above reaction is:

[tex] Ka = \frac{[C_{9}H_{7}O_{4}^{-}][H_{3}O^{+}]}{[C_{9}H_{8}O_{4}]} [/tex]

[tex] Ka = \frac{x^{2}}{0.02 - x} [/tex]

To find Ka we need to find the value of x. We know that pH = 2.6 so:

[tex] pH = -log[H_{3}O^{+}] [/tex]

[tex] 2.6 = -log(x) [/tex]

[tex] x = 2.51 \cdot 10^{-3} M = [H_{3}O^{+}] = [C_{9}H_{7}O_{4}^{-}] [/tex]

Now, the concentration of C₉H₈O₄ is:

[tex] C_{C_{9}H_{8}O_{4}} = 0.02 - 2.51 \cdot 10^{-3} = 0.018 M [/tex]

Finally, Ka is:

[tex] Ka = \frac{[C_{9}H_{7}O_{4}^{-}][H_{3}O^{+}]}{[C_{9}H_{8}O_{4}]} = \frac{(2.51 \cdot 10^{-3})^{2}}{0.018} = 3.50 \cdot 10^{-4} [/tex]

Therefore, the Ka of aspirin is 3.50x10⁻⁴.

       

I hope it helps you!

Which statements best describe half lives of radioactive isotopes

Answers

You should also add the statements

Answer:

The half-life varies depending on the isotope.

Half-lives range from fractions of a second to billions of years.

The half-life of a particular isotope is constant.

Explanation:

Make sure you add the options

Determine ΔH for the reaction CaCO3 → CaO + CO2 given these data: 2 Ca + 2 C + 3 O2 → 2 CaCO3 ΔH = −2,414 kJ C + O2 → CO2 ΔH = −393.5 kJ 2 Ca + O2 → 2 CaO ΔH = −1,270 kJ Write your answer using 4 significant figures, do not include units.

Answers

Answer:

The ΔH for the reaction is -456.5 KJ

Explanation:

Here we want to determine ΔH for the reaction;

Mathematically;

ΔH = ΔH(product) - ΔH(reactant)

In the case of the first reaction;

ΔH = ΔH(CaO) + ΔH(CO2) - ΔH(CaCO3)  ...........................(*)

From the other reactions, we can get the respective ΔH for the individual molecule in the reaction

In second reaction;

Kindly note that for elements, molecule of gases, ΔH = 0

What this means is that throughout the solution;

ΔH(Ca)  = 0 KJ

ΔH(O2) = 0 KJ

ΔH(C) = 0 KJ

Thus, in writing the equation for the subsequent chemical reactions, we shall need to write and equate the overall ΔH for the reaction to that of the product alone

So in the second reaction

ΔH = 2ΔH(CaCO3)

Thus;

-2414/2 = ΔH(CaCO3)

ΔH(CaCO3) = -1,207  KJ

Moving to the third reaction, we have;

ΔH = ΔH(CO2)

Hence ΔH(CO2) = -393.5 KJ

For the last reaction;

ΔH = ΔH(CaO)

Hence ΔH(CaO) = -1270 KJ

Going back to equation *

ΔH = ΔH(CaO) + ΔH(CO2) - ΔH(CaCO3)

Using the values of the ΔH  of the respective molecules given above,

ΔH  = -1270 + (-393.5) - (-1207)

ΔH  = -456.5 KJ


1. What step dogs every scientific experiment begin with?
A hypothesis
B. procedures
C conclusion
D. question/problem

Answers

i believe D) question/problem
it’s a question/ problem

You need to make an aqueous solution of 0.243 M iron(III) chloride for an experiment in lab, using a 125 mL volumetric flask. How much solid iron(III) chloride should you add?

Answers

Answer:

5 g

Explanation:

From the question, we have,

Molarity of FeIII solution= 0.245 M

Volume of solution = 125 ml

From

number of moles= concentration × volume

We have;

Number of moles= 0.245 M × 125/1000

Number of moles = 0.031 moles

Molar mass of Fe III = 162.5g/moles

Mass of iron III = number of moles× molar mass = 0.031 × 162.5= 5 g

n

Nicotinic acid, HC6H4NO2, is a B vitamin. It is also a weak acid with Ka = 1.4 × 10-5. Calculate [H+] and the pH of a 0.041 M solution of HC6H4NO2.

Answers

Answer:

[H+] = 7.576x10⁻⁴M

pH = 3.12

Explanation:

Based on the equilibrium of the nicotinic acid in water:

HC6H4NO2(aq) + H2O(l) ⇄ C6H4NO2-(aq) + H3O+(aq)

Ka = [C6H4NO2-] [H3O+] / [HC6H4NO2]

As both C6H4NO2-(aq) and H3O+(aq) comes from the same equilibrium, we can approximate their concentration as X and replace:

Ka = [C6H4NO2-] [H3O+] / [HC6H4NO2]

1.4x10⁻⁵ = [X] [X] / [0.041M]

5.47x10⁻⁷ = X²

7.576x10⁻⁴M = X = [H+]

And as pH is defined as -log [H⁺]

pH = 3.12

The water bottle contains 575 grams of water at 80°C. The water eventually cools to

40°C. How many calories of heat could be transferred to the student's back?

Answers

Answer:

–23000 Calories.

NOTE : The negative sign indicates that heat has been loss to the student back.

Explanation:

The following data were obtained from the question:

Mass (M) of water = 575 g

Initial temperature (T1) = 80 °C

Final temperature (T2) = 40 °C

Heat (Q) transferred =.?

Next, we shall determine the change in temperature (ΔT).

This is illustrated below:

Initial temperature (T1) = 80 °C

Final temperature (T2) = 40 °C

Change in temperature (ΔT) =?

Change in temperature (ΔT) = T2 – T1

Change in temperature (ΔT) = 40 – 80

Change in temperature (ΔT) = –40°C

Finally, we shall determine the heat transferred. This can be obtained as follow:

Mass (M) of water = 575 g

Change in temperature (ΔT) = –40°C

Specific heat capacity (C) of water = 1 Cal/g°C

Heat (Q) transferred =.?

Q = MCΔT

Q = 575 × 1 × –40

Q = –23000 Calories

NOTE : The negative sign indicates that heat has been loss to the student back.

The chemical formula for sumuric acid is H Son. In one molecule of sulfuric acid, there are____
A. two atoms of hellum
B. two atoms of oxygen
C. four atoms of oxygen
D. four atoms of sulfur oxide

Answers

Answer:

I want to say option C: four atoms of oxygen. Sorry if I'm wrong

A. In a separatory funnel containing ethyl acetate and 10% aqueous sodium bicarbonate (NaHCO3), which layer would contain the brominated aromatic compound?

Answers

Answer:

ethyl acetate layer

Explanation:

This question tests your knowledge of the principle of solvent extraction.

In solvent extraction, there is always an organic layer and an aqueous layer. The ethyl acetate is the organic layer while the sodium bicarbonate is the aqueous layer.

A brominated aromatic compound will be extracted into the organic layer (ethyl acetate layer).

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