Unit 4.2 quiz chemistry

A

because both have 2's in front of them

Answer:

d

Explanation:

answer d makes the equation balance

Answer:

Explanation:

[tex]\text{From the information given:}[/tex]

[tex]\text{The chemical reaction is : } 4 KClO_{3(s)} \to 3 KClO_{4(s)} + KCl_{(s)}[/tex]

[tex]\text{To find} \ \Delta G^0_{rxn}\ \text{using the formula}: \\ \\ \Delta G^0_{rxn} = \sum n_p \times \Delta _f G^0 (Products) - \sum n_R \times \Delta _fG^0 ( Reactants) \\ \\ where; n_p = \text{no of moles of products } \ and; \\ \\ n_R = \text{no of moles of reactants }[/tex]

[tex]\implies G^0_{rxn} = 3 \times \Delta _fG^0 [KClO_4{(s)}] + \Delta_fG^0[KCl_{(s)}] - 4 \times \Delta _f G^0 [ KClO_3 (s) ][/tex]

[tex]\Delta _fG^0 \ values \ at \ 25^0 \ C (298 \ K) are\ given \ as:\\\\ \Delta _fG^0 [KClO_4(s)] = -303.09 \ kJ \\ \\ \Delta _fG^0 [KCl(s) ] = - 409.14 \ kJ \\ \\ \Delta_f G^0 [KClO_3_{(s)}] = -296.25 \ kJ \\ \\ replacing \ the \ above \ values \ into \ equation (1) ; then:\\ \\ \\\Delta G^0_{rxn} = 3 *(-303.09) + (-409.14) - 4*(-296.25) \ kJ \\ \\ = (-909.27 - 409.14 + 1185) \ kJ \\ \\ = -133.41 \ kJ \\ \\ \mathbf{\Delta G^0_{rxn} = -133.4 \ kJ }[/tex]

The standard free energy change of the reaction is -133 kJ.

From the reaction equation, we have; 4KClO3 ⇄ 3KClO4 (s) + KCl (s). The standard free energy of formation of each specie is given below;

ΔG°f KClO3 = -296.35 kJ

ΔG°f KClO4 = -303.09 kJ

ΔG°f KCl = -409.14 kJ

Hence;

ΔG°rxn = [3(-303.09)] + ( -409.14)] - [(4( -296.35))]

ΔG°rxn = (-909.27) + (-409.14) - (-1185.4)

ΔG°rxn = -133 kJ

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Answer:

it's a double displacement Reaction.

Answer:

Neil Bohr

Explanation:

Thank me latur✊

Answer:

Coal

Explanation:

thx for points :D

Answer:

Coal

Explanation:

your welcome<3

Answer:

pentanoic acid

Explanation:

it has 5 carbon atoms which gives it the parent name pent, and its attached to the ester group

Answer: Dynamic equilibrium

Explanation:

Answer:

H₂SO₄ is the correct answer sorry im late

Answer: D

Explanation:

Radiation from gamma decay has the most energy and the correct option is option D.

To become more stable, the nuclei undergo radioactive decay. In this process, the nuclei give off energy and may also emit charged particles of matter.

Types of radioactive decay include alpha, beta, and gamma decay. In alpha and beta decay, both particles and energy are emitted. In gamma decay, only energy, in the form of gamma rays, is emitted.

In the gamma decay, a nucleus changes from a higher energy state to a lower energy state through the emission of electromagnetic radiation.

Therefore, Radiation from gamma decay has the most energy and the correct option is option D.

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Answer:

Student 4

Explanation:

In the structure of the atom of an element, there are protons, electrons and neutrons. The number of protons in the atom of such element determines the atomic number of the element. For example, if Calcium contains 20 protons, the atomic no of Calcium will be 20. Since this is so, it means that the identity of an element on the periodic table can be known using the number of protons/atomic no.

According to this question, four students are gathering information on elements to determine their identity. Based on the explanation above, it takes only the number of protons = atomic no. of the element to identify it. Hence, student 4, who counts the number of protons will correctly identify the element using his/her data.

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Answer: HBr + NaOH = nabr + h2o

Explanation:

I hope this helped!

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Answer:

Retention factor or [tex]R_f[/tex] value is defined as the ratio of distance traveled by the unknown to the distance traveled by the solvent front.

[tex]R_f=\frac{\text{ distance by unknown}}{\text {distance by solvent}}[/tex]

Putting in the values we get:

[tex]R_f_{X}=\frac{0.50cm}{3.0cm}=0.16[/tex]

[tex]R_f_{Y}=\frac{1.0cm}{3.0cm}=0.33[/tex]

As the [tex]R_f[/tex] value of Y is more than X , it follows that Y compound will be retained less strongly than the compound X. Thus Y is more polar than X.

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Answer: Weak base

Explanation:

I hope this helped!

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Answer and Explanation:

Solutions that have a pH of 8 would be considered a Weak Base.

This is because a weak base is a base that, upon dissolution in water, does not dissociate completely.

Solutions/liquids that have a pH higher than a pH of 7 are basic solutions, while solutions/liquids that have a pH lower than a pH of 7 are acidic solutions.

When the pH level is closer to 7, it is weak, and when it is far from 7, like if it is 1 or 12, then it is a strong acid/base.

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Answer:

Fe + 3CuNO₃ → Fe(NO₃)₃ + 3Cu

Explanation:

Writing the equation using symbols leaves us with:

It is not balanced yet. Now we balance the NO₃ species on the left side:

Finally we balance the Cu species on the right side:

Answer:

0.147 Hz   because I took the test

The velocity of a wave is the product of its frequency and wavelength. The  velocity of wave with 0.147 Hz and 12.05 m is 1.77 m/s.

The frequency of a wave is the number of wave cycles per unit time. Frequency is the inverse of time period of the wave. It is inversely proportional to the wavelength. Unit of frequency is Hz which is equivalent to s⁻¹.

The wavelength of a wave is the distance between two consecutive crests or troughs. The wavelength λ, and frequency ν of a wave is related to the velocity  v of the wave as follows:

v = νλ

Given that,

frequency = 0.147 Hz

wavelength = 12.05 m

then, velocity = 0.147 Hz × 12.05 m = 1.77 m/s.

Therefore, the velocity of the mechanical wave is 1.77 m/s.

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Answer:

4/15

Explanation:

we can write out an equation by doing (1/5 ÷ 3/4) and then switch the sign to multiplication and we can keep the first fraction the same (in this case 1/5) and then we flip the second fraction BUT when we flip the second fraction upside-down we have to change the symbol to multiplication (1/5x4/3)

then after that all we do is multiply the denominators and numerators :)

1 x 4 = 4

_______

5 x 3 = 15

answer would be 4/15

Answer:

16.51%

Explanation:

The reaction that takes place is

Meaning that the white precipitate that formed is AgCl. Now we convert 0.535 g of AgCl into moles, using its molar mass:

Then we convert 0.00373 moles of AgCl into moles of CaCl₂, using the stoichiometric coefficients:

We convert moles of CaCl₂ into grams, using its molar mass:

Finally we calculate the percent of CaCl₂ by mass in the original mixture:

The percent calcium chloride by mass in the original mixture is 16.4%

The equation of the reaction between calcium nitrate and silver chloride is:

[tex]\mathbf{CaCl_2 + 2AgNO_3 \to 2 AgCl+Ca(NO_3)_2}[/tex]

Given that;

the number of moles of the precipitated AgCl is:

= 0.535 g / 143.32 g/mol

= 0.0037 moles

From the above reaction, If 2 moles of AgCl are formed  by 1 mole of CaCl2

Then, 0.0037 moles of AgCl will form (0.0037 × 1)/2 moles of CaCl2.

0.0037 moles of AgCl will form 0.00185 moles of CaCl2.

Now, we can say that the number of moles of CaCl2 present in the mixture is =  0.00185 moles

Mass amount of CaCl2 present = 0.00185 moles × 110.98 g/mol

Mass amount of CaCl2 present = 0.205 grams

Finally, the mass percentage   [tex]\mathbf{=\dfrac{0.205}{1.25}\times 100\%}[/tex]

= 16.4%

Therefore, we can conclude that the percent calcium chloride by mass in the original mixture is 16.4%

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Answer:

2.64 M

Explanation:

Use the dilution equation M1V1 = M2V2, where:

M1 = 12.0 M HCl

V1 = 220 mL HCl

M2 = ?

V2 = 1000 mL HCl

(12.0 M HCl)(220 mL HCl) = M2(1000 mL HCl)

M2 = 2.64 M HCl

Answer:

hi

Explanation:

i am smart but i need this app cuz some are realy hard

Answer:

Explanation:

Mass of uncrystallized product = (Mass of watch glass + filter paper + crystallized product) - (Mass of watch glass + filter paper)  

Mass of uncreystaliized product = 109.03 gm - 105.98 gm

Mass of uncrystaliized product = 3.05 gm

For methyl benzoate;

mass = 3.08 g

no of moles = 3.08 g/ 136.15 g/mol = 0.0226 mole

It is possible for the formation of 1 mole of nitro methyl benzoate from a mole of methyl benzoate.

moles of nitro methyl benzoate that can be formed from 0.0226 moles of methyl benzoate = 0.0226 moles

∴

mass of nitro methyl benzoate = 0.0226 mol × 181.15 gm /mol

mass of nitro methyl benzoate = 4.098 gm

For HNO_3 solution:

mass = 1.42 gm/ml × 2.0 ml

mass = 2.84 gm

Mass of HNO3 in 2.84 gm solution[tex](69\% w/w)= 2.84 gm * \dfrac{69}{100 }[/tex]

= 1.9596 gm

Moles of HNO3 = [tex]\dfrac{ 1.9596 \ gm }{ 63.01 gm /mol}[/tex]

= 0.0311 mole

1 mol of HNO_3 can be formed from 1 mole of nitro methyl benzoate

Thus; moles of nitro methyl benzoate that can be formed from 0.0311 mole of HNO_3 = 0.02256 mole

The mass for nitro methyl benzoate can now be determined as:

= 0.0311 mole × 181.5 gm/mole

= 5.634 gm

Since the mass formed from methyl benzoate is lesser, then methyl benzoate serves as the limiting reagent.

The mass obtainable from the LR = 4.098 gm

Answer:

You will know if elements have the same properties if they are in the same column (up and down) on the periodic table.

Explanation:

Ex: Lithium and a hydrogren has the same properites bcause they are both on the same line/column. Columns are up and down the table and rows are left and right. Hope this helps

Answer:  60.7 g of [tex]PH_3[/tex] will be formed.

Explanation:

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given volume}}{\text{Molar volume}}[/tex]    

[tex]\text{Moles of} H_2=\frac{60L}{22.4L}=2.68moles[/tex]

The balanced chemical reaction is

[tex]P_4(s)+6H_2(g)\rightarrow 4PH_3(g)[/tex]

[tex]H_2[/tex] is the limiting reagent as it limits the formation of product and [tex]P_4[/tex] is the excess reagent.

According to stoichiometry :

6 moles of [tex]H_2[/tex] produce = 4 moles of [tex]PH_3[/tex]

Thus 2.68 moles of [tex]H_2[/tex] will produce=[tex]\frac{4}{6}\times 2.68=1.79moles[/tex]  of [tex]PH_3[/tex]

Mass of [tex]PH_3=moles\times {\text {Molar mass}}=1.79moles\times 33.9g/mol=60.7g[/tex]

Thus 60.7 g of [tex]PH_3[/tex] will be formed by reactiong 60 L of hydrogen gas with an excess of [tex]P_4[/tex]

Answer:

pH of the solution will decrease & hydronium ion concentration will increase in the solution as the acid is added.

Explanation:

Explanation:

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Answer: d. Determining empirical formula

Explanation:

Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.  

Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.

Step 1: If percentage are given then we are taking total mass is 100 grams.  So, the mass of each element is equal to the percentage given.

Step 2 : convert given masses into moles

Step 3 : For the mole ratio, divide each value of moles by the smallest number of moles calculated

Step 4: The mole ratio gives the empirical formula of the compund.

Answer:

[tex]2Fe +N_{2} -> 2FeN[/tex]

Explanation:

Iron is Fe, nitrogen is N. Nitrogen is diatomic, which means it occurs as a molecular pair by itself. Iron III nitride has a chemical formula of FeN because nitrogen has a charge of 3-, and iron III tells us the iron has a charge of 3+ so you just need one of each to make the charges balance and the compound neutral.

When iron reacts with nitrogen to form iron(III) nitride, the balanced chemical equation of this reaction is as follows:

2 Fe + N₂ → 2FeN

The term balanced chemical equation is defined as a chemical equation in which mass is conserved and there are equal numbers of atoms of each element on both sides of the equation.

The chemical equation must be balanced in order to obey the law of conservation of mass. When the number of different atoms of elements in the reactants side equals the number of atoms in the products side, the chemical equation is balanced.

Nitrogen is diatomic, that means it occurs as a molecular pair by itself. Iron III nitride has a chemical formula of FeN because nitrogen has a charge of 3-, and iron III tells us the iron has a charge of 3+ .

Thus, iron reacts with nitrogen to form iron(III) nitride.

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