Question 1 (1 point)
A chemical reaction is when substances are changed into other substances.

True or False

The concentrations : 0.15 M

pH=11.21

The ionization of ammonia in water :

NH₃+H₂O⇒NH₄OH

NH₃+H₂O⇒NH₄⁺ + OH⁻

The concentrations of all species present in the solution = 0.15 M

Kb=1.8 x 10⁻⁵

M=0.15

[tex]\tt [OH^-]=\sqrt{Kb.M}\\\\(OH^-]=\sqrt{1.8\times 10^{-5}\times 0.15}\\\\(OH^-]=\sqrt{2.7\times 10^{-6}}=1.64\times 10^{-3}[/tex]

[tex]\tt pOH=-log[OH^-]\\\\pOH=3-log~1.64=2.79\\\\pH=14-2.79=11.21[/tex]

Taking into account the reaction stoichiometry and the definition of molarity, 175 mL of 2 M H₂SO₄ will react with 28.0 g of NaOH.

In first place, the balanced reaction is:

H₂SO₄ + 2 NaOH  → Na₂SO₄ + 2 H₂O

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:

The molar mass of the compounds is:

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

Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

[tex]Molarity= \frac{number of moles}{volume}[/tex]

Molarity is expressed in units [tex]\frac{moles}{liter}[/tex].

The following rule of three can be applied: If by reaction stoichiometry 80 grams of NaOH react with 1 mole of H₂SO₄, 28 grams of NaOH react with how many moles of H₂SO₄?

[tex]moles of H_{2}S O_{4} =\frac{28 grams of NaOHx1 mole ofH_{2}S O_{4} }{80 grams of NaOH}[/tex]

moles of H₂SO₄= 0.35 moles

In this case, you know:

Replacing in the definition of molarity:

[tex]2 \frac{moles}{liter}= \frac{0.35 moles}{volume}[/tex]

Solving:

2 [tex]\frac{moles}{liter}[/tex] × volume= 0.35 moles

volume= 0.35 moles ÷ 2 [tex]\frac{moles}{liter}[/tex]

volume= 0.175 liters= 175 mL (being 1 L= 1000 mL)

Finally, 175 mL of 2 M H₂SO₄ will react with 28.0 g of NaOH.

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Answer:

The answer is B

Explanation:

I had the same question and I chose B and it was correct.

Answer:

B. Carbon needs more than just three bonds to reach a noble gas

Explanation:

PLATO ANSWER

PLATO EXPLANATION-

Each hydrogen atom can make only one bond, but a carbon atom needs four bonds to be stable. Therefore, three hydrogen atoms are not enough for the carbon atom to make four bonds.

Answer:

This question is incomplete

Explanation:

This question is incomplete but the answer to the question can be correctly predicted from the available information from the question.

1. If a "container" (in this case a crucible) is closed throughout a heating experiment. Then it must be noted that water vapor will not be able to escape during the course of the experiment. The water vapor will form a "cloud" of water droplets under the cover of the crucible. And when this crucible is cooled, this water droplets return back to the content/substance inside the crucible.

2. When compared with the initial amount of water present in the substance in the crucible, the percentage of water "left" in the hydrate or substance in the crucible would be high. This is because the water vapor that was suppose to leave the crucible did not leave because the crucible was closed (thus causing very low amount of water vapour to leave).

Because of the student error, the percent water of crystallization value the hydrate will be lower than its actual value.

Evaporation is the process by which a liquid changes spontaneously to vapor.

In the experiment to determine percentage water of crystallization, the crucible is left open to ensure all the water molecules are removed by evaporation.

However,, since the student did not remove the crucible cover during heating, some water molecules will not be able to escape completely, but will return back to the salt.

Hence, the percent water of crystallization value the hydrate will be lower because the of mass of the anhydrous salt will be higher than its actual value.

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Answer:

1.1 M

General Formulas and Concepts:

Explanation:

Step 1: Define variables

1.2 mol KCL

1.1 L of solution

M = unknown

Step 2: Solve for Molarity

Step 3: Check

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

1.09091 M ≈ 1.1 M

Answer: C

Explanation:

No matter the location on Earth, the sun always rises in the east due to its rotation pattern.

Answer:

Molar mass of NH4SO2=104gmol`

No of moles of NH4SO2=2.3g/104gmol`=0.022×(avagadro's constant)

Answer:

Universe.

Explanation:

Biosphere is just a planet. Solar system contains planets and star. Galaxy holds multiple solar systems only. Universe hold everything, biospheres, solar systems, and galaxies. I hope this helps :D

Answer:

B.

Explanation:

A solar system is IN a galaxy. Its not A.

A Galaxy doesnt have other galaxies in it. Its not c

A biosphere is only referring to earth. its not D.

Therefore, it is B. A universe is everything in outer space including stars, planets, and galaxies.

Answer:

Adenine pairs with thymine and guanine pairs with cytosine

Answer:

46.32 mL

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

2HNO₃ + Ca(OH)₂ —> Ca(NO₃)₂ + 2H₂O

From the balanced equation above,

The following data were obtained:

Mole ratio of the acid, HNO₃ (nA) = 2

Mole ratio of the base, Ca(OH)₂ (nB) = 1

Next, we shall write out the data obtained from the question. This includes:

Molarity of the acid, HNO₃ (Ma) = 0.181 M

Volume of the base, Ca(OH)₂ (Vb) = 25.1 mL

Molarity of the base, Ca(OH)₂ (Mb) = 0.167 M

Volume of the acid, HNO₃ (Va) =?

Finally, we shall determine the volume of the acid, HNO₃ as shown below:

MaVa/ MbVb = nA/nB

0.181 × Va / 0.167 × 25.1 = 2/1

0.181 × Va / 4.1917 = 2

Cross multiply

0.181 × Va = 4.1917 × 2

0.181 × Va = 8.3834

Divide both side by 0.181

Va = 8.3834 / 0.181

Va = 46.32 mL

Therefore, the nitric acid, HNO₃ required for the reaction is 46.32 mL

Answer:

-114kJ mol-1

Explanation:

Definition of the enthalpy change of neutralization: the energy released with the formation of 1 mole of water when neutralization takes place between an acid and a base.

Since both reactions yield the same number of moles of water, the answer should be -114kJ mol-1.

The statement for the enthalpy change of reaction 2 is "-114 kJ"

The change in enthalpy (ΔH) is a quantity of heat of a system. The enthalpy change is the amount of heat that enters or exits a system during a reaction.

One equivalent of hydrogen ions is neutralised with one equivalent of hydroxide ions in the reaction 1,

NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

The change in enthalpy is given as -114 kJ.

Two equivalents of hydrogen ions are neutralised with two equivalents of hydroxide ions in the reaction 2,

Ba(OH)2 + H2SO4 (aq) → BaSO4 (s) + 2H2O (l)

But, that primary ionic reaction is same for both the reaction in which hydrogen ion combines with hydroxide ion to generate a water molecule. So, the enthalpy change of reaction 1 would be exactly same as for reaction 2.

The neutralization enthalpy comes out to be -114 kJ.

Hence the correct answer is -114 kJ.

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Answer:

6.711 × 10²⁴ molecules Mg(OH)₂

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

650.0 g Mg(OH)₂

Step 2: Define conversions

Avogadro's Number

Molar Mass of Mg - 24.31 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of H - 1.01 g/mol

Molar Mass of Mg(OH)₂ - 24.31 + 2(16.00) + 2(1.01) = 58.33 g/mol

Step 3: Convert

[tex]650.0 \ g \ Mg(OH)_2(\frac{1 \ mol \ Mg(OH)_2}{58.33 \ g \ Mg(OH)_2} )(\frac{6.022 \cdot 10^{23} \ molecules \ Mg(OH)_2}{1 \ mol \ Mg(OH)_2} )[/tex]

= 6.71061 × 10²⁴ molecules Mg(OH)₂

Step 4: Check

We are given 4 sig figs. Follow sig fig rules.

6.71061 × 10²⁴ molecules Mg(OH)₂ ≈ 6.711 × 10²⁴ molecules Mg(OH)₂

Answer:

Increases

Explanation:

The gravitational potential energy of an object increases as you bring it higher with respect to the ground.

Gravitational potential energy depends on the mass, height and gravity between two bodies;

   Gravitational potential energy  = mgh

m is the mass

g is the height

h is the height

Answer:

Ionic

Explanation:

Because sulphur is a non-metal and cesium is part of the group 1 Alkali Metals, this creates an ionic bond

Ionic bonds are created from one metal and one non-metal element.

This still is declared as Ionic despite the balance of this is Cs2S

Answer:

The magnesium ion is much smaller than the magnesium atom because magnesium atom contains more electrons as compared to magnesium ion. Explanation: ... Whereas when an atom tends to lose an electron then it acquires a positive charge and size of the atom tends to increase.

Answer:

Because it looses it two electrons to form a stable octet Ionic form..........

Answer:

d. It's ability to lose electrons

Answer:

Mass of CO₂ produced = 20.328 g

Oxygen is limiting reagent.

Explanation:

Given data:

Mass of C₂H₂ = 13.7 g

Mass of O₂ = 18.5 g

Mass of CO₂ produced = ?

What is limiting reagent = ?

Solution:

Chemical equation:

2C₂H₂ + 5O₂      →     4CO₂ + 2H₂O

Number of moles of C₂H₂:

Number of moles = mass /molar mass

Number of moles = 13.7 g/ 26.04 g/mol

Number of moles = 0.526 mol

Number of moles of O₂:

Number of moles = mass /molar mass

Number of moles = 18.5 g/ 32 g/mol

Number of moles = 0.578 mol

Now we will compare the moles of CO₂ with C₂H₂ and O₂

                      C₂H₂              :                CO₂

                           2                :                 4

                       0.526            :              4/2×0.526 = 1.052

                      O₂                  :                   CO₂

                        5                   :                     4

                      0.578             :                4/5×0.578 = 0.462

The number of moles of  CO₂ produced by O₂  are less thus oxygen will be limiting reactant.

Mass of CO₂ produced:

Mass = number of moles × molar mass

Mass = 0.462 mol × 44 g/mol

Mass = 20.328 g

Answer:

3.64g

Explanation:

Given parameters:

Mass of NH₃  = 18.1g

Mass of Cu₂O  = 90.4g

Unknown:

Limiting reactant  = ?

Mass of N₂ formed  = ?

Solution:

The reaction equation is given as:

       Cu₂O + 2NH₃ → 6Cu + N₂ + 3H₂O

The limiting reactant is the one in short supply in the reaction. Let us find the number of moles of the given species;

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

Molar mass of Cu₂O = 2(63.6) + 16  = 143.2g/mol

Molar mass of NH₃  = 14 + 3(1) = 17g/mol

Number of moles of Cu₂O = [tex]\frac{18.1}{143.2}[/tex]   = 0.13moles

Number of moles of NH₃   = [tex]\frac{90.4}{17}[/tex]   = 5.32moles

  From this reaction;

       1 mole of  Cu₂O combines with 2 mole of NH₃

So   0.13moles of  Cu₂O will combine with 0.13 x 2 mole of NH₃

                                              = 0.26moles of NH₃

Therefore, Cu₂O is the limiting reactant. Ammonia is in excess;

Mass of N₂;

   Mass = number of moles x molar mass

    1 mole of Cu₂O  will produce 1 mole of N₂

    0.13 mole of Cu₂O  will produce 0.13 mole of N₂

    Mass  = 0.13 x (2 x 14) = 3.64g

Answer:

Watch Naruto that's the answer

Explanation:

Percent by mass : 4.10⁺³%

The concentration of a solution can be expressed in units such as molarity, normality, mass percent, volume percent etc.

[tex]\tt \%mass=\dfrac{mass~solute}{mass~solution}\times 100\%[/tex]

mass solute= mass of NaOH  

mass of NaOH :

[tex]\tt 0.001~mol/L\times 1~L\times 40~g/mol=0.04~g[/tex]

mass solution = 1000 g

% mass :

[tex]\tt \dfrac{0.04}{1000}\times 100=4.10^{-3}\%[/tex]

The percent by mass concentration of NaOH in the given solution is approximately 0.004%.

To calculate the percent by mass concentration of NaOH, we must find the mass of NaOH in solution.

First, we determine how many moles of NaOH are present in the solution:

Molarity (M) is calculated as moles of solute per liter of solution.

1 L = 0.001 M = mole of NaOH

We rearrange the equation to find that one mole of NaOH is equal to 0.001 moles.

Mass of NaOH = moles of NaOH * molar mass of NaOH

Mass of NaOH = 0.001 mol * 40.00 g/mol

Mass of NaOH = 0.04 g

The mass of the solution is 1000 g which is given in the question.

Percent by mass concentration of NaOH = (mass of NaOH / mass of solution) * 100%

Percent by mass concentration of NaOH = (0.04 g / 1000 g) * 100%

Percent by mass concentration of NaOH = 0.004%

Hence, the percent by mass concentration of NaOH in the given solution is approximately 0.004%.

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The work energy of this process : 2337.298 J

The laws of thermodynamics 1 state that: energy can be changed but cannot be destroyed or created  

ΔU=Q-W

Q=m.c.Δt

[tex]\tt Q=8.85\times 2.650\times 63.2=1482.198~J[/tex]

the work (W) :

[tex]\tt W=Q-\Delta U\\\\W=1482.198-(-855.1)=2337.298~J[/tex]

Answer:

[tex]T_f=26.7\°C[/tex]

Explanation:

Hello.

In this case, when two substances at different temperature are placed in contact in an isolated container, we can say that the heat lost by the hot substance is gained by the cold substance. In such a way, since granite is at 76.0 °C and water at 22.0 °C we infer granite is hot and water is cold, so we write:

[tex]Q_{granite}=-Q_{water}[/tex]

In terms of mass, specific heat and change in temperature, we write:

[tex]m_{granite}C_{granite}(T_f-T_{granite})=-m_{water}C_{water}(T_f-T_{water})[/tex]

Thus, since the temperature is the same for both substance, we can solve for it as shown below:

[tex]T_f=\frac{m_{granite}C_{granite}T_{granite}+m_{water}C_{water}T_{water}}{m_{granite}C_{granite}+m_{water}C_{water}}[/tex]

By plugging in each variable, we obtain:

[tex]T_f=\frac{11.1g*0.790\frac{J}{g\°C} *76.0\°C+22.0g*4.18\frac{J}{g\°C} *22.0\°C}{11.1g*0.790\frac{J}{g\°C} +22.0g*4.18\frac{J}{g\°C}}\\\\T_f=26.7\°C[/tex]

Best regards!

Answer:

The advantages of using an indicator to inform pH measurements:

It gives a mathematically result of the pH, in addition, it gives the precise pH of solvent, and it also gives an idea of the straight of the solution also.

Now, the advantage of using a pH meter:

It is a rapid method to characterize between acids, bases. However, this method does not show how strong acid or base actually are, plus it tends to gives a range of acidity or basicity not quite accurate as a result.

Answer:

Explanation:

no of molecules=5.65*10^21

NA=6.23*10^23

no of moles=no of molecules/avogadro number

no of moles=5.65*10^21/6.23*10^23

no of moles=9.07*10^-3

now we know that

no of moles=mass/molar mass

mass=no of moles*molar mass

mass=9.07*10^-3*89.06

mass=0.808 g

Answer:

no one additions exceed the capacity of the buffer

Explanation:

given

Volume buffer = 500.0 mL = 0.5 L

mol HNO₂ = 0.5 L × 0.100 mol/L = 0.05 mol HNO₂

mol NO₂⁻ = 0.5 L × 0.150 mol/L = 0.075 mol NO₂⁻

solution

we know when any base more than 0.05 (HNO2) than exceed buffer capacity

and when any base more than 0.075 (KNO2) than exceed buffer capacity

when we add 250 mg NaOH (0.250 g)

than molar mass NaOH =40 g/mol

and mol NaOH = 0.250 g ÷ 40g/mol

mol NaOH  = 0.00625 mol

0.00625 mol NaOH will be neutralized by 0.00625 mol HNO₂

so it would not exceed the capacity of the buffer.

and

when we add 350 mg KOH (0.350 g)

than molar mass KOH =56.10 g

and mol KOH = 0.350 g ÷ 56.10 g/mol

mol KOH = 0.0062 mol

here also capacity of the buffer will not be exceeded

and

now we  add 1.25 g HBr

than molar mass HBr = 80.91 g/mol

and mol HBr = 1.25 g  ÷ 80.91 g/mol

mol HBr = 0.015 mol

0.015 mol Hbr will neutralize 0.015 mol NO₂⁻  

so the capacity will not be exceeded.

and

we add 1.35 g HI  

molar mass HI = 127.91 g/mol

so mol HI = 1.35 g ÷ 127.91 g/mol

mol HI = 0.011 mol

capacity of the buffer will not be exceed

Answer:

Mantle convection

Explanation:

The source of the force that moves tectonic plates along plate boundaries is as a result of the mantle convection.

Answer:

cheese and bread

Explanation:

2 bread 1 cheese = cheese sandwich

Answer:

5.00 moles O₂

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

3.01 × 10²⁴ molecules O₂

Step 2: Convert

[tex]3.01 \cdot 10^{24} \ mc \ O_2(\frac{1 \ mol \ O_2}{6.022 \cdot 10^{23} \ mc \ O_2} )[/tex] = 4.99834 moles O₂

Step 3: Check

We are given 3 sig figs. Follow sig fig rules and round.

4.99834 moles O₂ ≈ 5.00 moles O₂

Answer:

Graham's law states that the rate of diffusion or of effusion of a gas is inversely proportional to the square root of its molecular weight

Explanation: