A chemist dissolves 249.mg of pure perchloric acid in enough water to make up 380.mL of solution. Calculate the pH of the solution. Be sure your answer has the correct number of significant digits.

Answer:

1. There is no moles of water in 39g of chlorine.

2. 1.19x10²³ molecules of Au.

Explanation:

First, we need to remember that molar mass of a compound represents the mass of 1 mole (6.022x10²³ molecules) of molecules.

Molar mass of Chlorine, Cl₂ is 70.9g/mol

Molar mass of gold, Au, is 197g/mol

1. Moles of 39g of Cl₂ are:

39g Cl₂ * (1mol / 70.9g) = 0.55 moles moles of chlorine

But there is no moles of water in 39g of chlorine.

2. First, moles of Au are:

39g Au * (1mol / 197g) = 0.198 moles Au.

Molecules are:

0.198 moles Au * (6.022x10²³ molecules / 1 mol) =

Answer:

A

Explanation:

Answer: a

Explanation: one that changes the color of a rabbit, allowing it to hide from predators.

Answer:

303.4 millimeters

Explanation:

Just multiply 1.64 by 0.185. then convert that answer to millimeters

Answer:

2.43 moles of water are require.

Explanation:

Number of moles of water required = ?

Number of moles of NO₂ available = 7.30 mol

Solution:

Chemical equation:

3NO₂ + H₂O     →     NO + 2HNO₃

now we will compare the moles of NO₂ with H₂O.

                         NO₂           :            H₂O

                           3              :              1

                        7.30            :           1/3×7.30 = 2.43 mol

Answer:

Pretty sure the answer is d) cells come from nonliving objects

Explanation:

i just think i remember xd

Answer:

1. Vinca

2.Zinnia

3.Cornflower

4.Mariglod

4.Geranium

Explanation:

Thank u mark as brainliest

Answer:

8.4 moles

Explanation:

Al4C3 + 12 H2O ---> 4 Al(OH)3 + 3 CH4

100g of Al4C3 = 100/144 = 0.7 moles

from the reaction above,

1 mole of Al4C3 = 12 moles of water

0.7 moles of Al4C3 = x moles of water

x = 12×0.7/1 = 8.4 moles

Therefore 8.4 moles of water is needed to react with 100. g of al4c3

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The moles of water are needed to react with 100. g of al4c3 - 8.34 moles.

The reaction can be expressed as -

Al₄C₃ + 12 H₂O → 4 Al(OH)₃ + 3 CH₄

By the equation, it can be said that 1 equivalent of Al₄C₃ reacts with the equivalent of 12 H₂O to generate 4 Al(OH)₃ and 3 CH₄.

the moles = mass + molar mass

then for moles of Al₄C₃ = 100 + 143.959

= 0.6946 moles.

or, 216/143.959

for 100 gram = 21600/143.959

= 150. 0416

moles of H₂O required = [tex]\frac{12\ mole\ of H_{2} O}{1\ mole\ of\ Al_{4} C_{3}}[/tex]

= 150.0416/18

= 8.43 moles.

Thus, the moles of water are needed to react with 100. g of al4c3 - 8.34 moles.

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Answer:

Molality = 0.43 m

Explanation:

Given data:

Mass of barium sulfide = 25.4 g

Mass of water = 349 g (349 g/1000 = 0.349 Kg)

Molality of water = ?

Solution:

Number of moles of barium sulfide:

Number of moles = mass/molar mass

Number of moles = 25.4 g/169.39 g/mol

Number of moles = 0.15 mol

Molality:

Molality = number of moles o f solute/ Kg of solvent

Molality = 0.15 mol / 0.349 Kg

Molality = 0.43 m

Ionic compounds have higher melting point than covalent compounds.

Carbon dioxide have lower melting point (-56.6 °C) among the given compounds.

Melting point is the temperature at which the substance melts into liquid thus at this temperature its solid state and liquid state are in equilibrium. Melting point is depend upon the bond type and mass of the compound.

Ionic bonds are stronger than covalent bonds and hence ionic compounds have higher melting point than covalent compounds. Hence, lithium chloride and calcium bromide have higher melting point.

Silicon is bigger than carbon thus silicon dioxide melts at higher temperature.  Carbon dioxide is purely covalent and melts at negative temperatures.

Hence, the compound with lower melting point here is carbon dioxide thus, option A is correct.

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Answer:

Coal is primarily used as fuel to generate electric power in the United States.

Explanation:

Answer:

-2

Explanation:

Magnesium usually has a negative charge.

Answer:

+2

Explanation:

Magnesium has the following electron configuration: 1s^2 2s^2 2p^6 3s^2 or [Ne] 3s2.

You can see that Magnesium contains two electrons in its outermost orbit. It loses these 2 electrons during the chemical reaction and transitions to the closest stable noble gas form. It also generates the Mg2+ ion as it loses two electrons. It has an ionic charge of 2+ as a result.

I hope you now fully comprehend why magnesium has a 2+ charge.

Answer:

Explanation:

The question states that the chemical equations should be balanced and the phases should also be indicated. The abbreviations of the phases have been indicated in the question with

i) (s) meaning the compound is in solid

ii) (aq) meaning the compound is in aqueous form

iii) (l) meaning the compound is in liquid

iv) (g) meaning the compound is in gaseous form

Balanced chemical equation is that in which the number of individual atoms on the reactant side is equivalent to the number of the same individual atoms on the product side.

Only the answer (the balanced chemical equations) will be written below.

A) This reaction is balanced

Mg(s) + Br₂(l) ⇒ MgBr₂(s)

B) P₄(s) + 5O₂(g) ⇒ P₄O₁₀ (s)

C) Ba(OH)₂(aq) + 2HNO₃(aq) ⇒ Ba(NO₃)₂(aq) + 2H₂O

D) Cr₂O₃(s) + 3C(s) ⇒ 2Cr(s) + 3CO(g)

Answer:

0.23J/g°C

Explanation:

Given parameters:

Mass of sample  = 135g

Amount of heat  = 2.5kJ

Initial temperature  = 19.5°c

Final temperature  = 100°C

Unknown:

Specific heat capacity of the metal  = ?

Solution:

The specific heat capacity of a substance is the amount of heat required to the raise the temperature of 1g of the substance by 1°C.

   H  = m C (T₂ - T₁ )

H is the amount of heat

m is the mass

C is the specific heat capacity

T₂ is the final temperature

T₁ is the initial temperature;

     2.5 x 10³  = 135 x C x (100 - 19.5)

     2500 = 10867.5C

       C = [tex]\frac{2500}{10867.5}[/tex]   = 0.23J/g°C

Answer:

donate? *transfer* (gain/lose, not share)

crystal

crystals (lattices)/ formula units

repeating (alternating) pattern (of +/- charges, like NaCl)

empirical

smallest

solid (...bc of strong bonds)

aqueous

Explanation:

An ionic bond forms when atoms transfer electrons.

Another name for an ionic compound is a crystal.

Instead of forming molecules, ionic compounds form.

Crystals are 3-dimensional arrays of positive and negative ions in a repeating pattern.

The formula for an ionic compound is called an empirical formula.

The formula for an ionic compound always indicates the smallest whole number ratio of positive to negative ions within the crystal.

Ionic compounds do not conduct electricity in the solid-state but do conduct electricity in the and states.

The aqueous state means that the compound is dissolved in water

An ionic bond is a bond that's formed when there's an electrostatic attraction between the oppositely charged ions. In this case, ionic bond forms when atoms transfer electrons.

It should also be noted that another name for an ionic compound is a crystal. Instead of forming molecules, ionic compounds form crystals.

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Complete Question

10 g of Compound X with molecular formula  [tex]C_4 H_8[/tex]  are burned in a constant-pressure calorimeter containing 45g of water at [tex]25^oC[/tex]. The temperature of the water is observed to rise by 2.432. (You may assume all the heat released by the reaction is absorbed by the water, and none by the calorimeter itself.) Calculate the standard heat of formation of Compound at [tex]25^oC[/tex]

Answer:

The value is  [tex]\Delta H^o_f =-2571 \ J /mol[/tex]

Explanation:

From the question we are told that  

    The mass of compound X is [tex]m = 10 \ g = 0.010 \ kg[/tex]

     The mass of water is  [tex]m_w = 45 \ g = 0.045 \ kg[/tex]

      The temperature of water is  [tex]T_w = 25^oC[/tex]

     The change in the temperature of water is  [tex]\Delta T = 2.432 ^oC[/tex]

Generally the heat adsorbed by water is mathematically represented as

         [tex]Q_{w } = c * m _w * \Delta T[/tex]

Here  c is the specific heat of water with value  [tex]c = 4186 \ J/kg\cdot ^oC[/tex]

         [tex]Q_{w } = 4186 * 0.045 * 2.432[/tex]

=>      [tex]Q_{w } = 458.1 \ J[/tex]

Given that the total heat that was generated by the reaction is absorbed by   water then

        [tex]\Delta H _{rxn} = -Q_w[/tex]

The negative sign shows that the heat was absorbed

        [tex]\Delta H _{rxn} = -458.1 \ J[/tex]

Generally the number of moles of the compound X available is mathematically represented as

              [tex]n = \frac{m}{Z}[/tex]

Here Z is the molar mass of compound X the value is [tex]Z = 56.11 \ g/mol[/tex]

             [tex]n = \frac{m}{Z}[/tex]

=>          [tex]n = \frac{10}{56.11}[/tex]

=>          [tex]n = 0.1782 \ mols[/tex]

Generally the standard heat of formation of Compound X is mathematically  represented as

            [tex]\Delta H^o_f = \frac{\Delta H_{rxn} }{ n}[/tex]

=>         [tex]\Delta H^o_f = \frac{-458.1 }{ 0.1782}[/tex]

=>         [tex]\Delta H^o_f = \frac{-458.1 }{ 0.1782}[/tex]

=>         [tex]\Delta H^o_f =-2571 \ J /mol[/tex]

Answer:

10.98 s

Explanation:

To solve this problem we first use the formula:

Where:

And solve for N:

Then we use the formula:

Where:

And solve for W₀.₅:

Answer:

Molarity of HCl solution = 0.25 M

Explanation:

Given data:

Volume of NaOH= V₁ = 25.0 mL (25/1000 = 0.025 L)

Molarity of NaOH solution=M₁ = 0.185 M

Volume of HCl solution = V₂ = 0.0200 L

Molarity of HCl solution =  M₂= ?

Solution:

M₁V₁   =  M₂V₂

0.185 M ×0.025 L =  M₂ × 0.0200 L

M₂  = 0.185 M ×0.025 L / 0.0200 L

M₂  = 0.005M.L /0.0200 L

M₂  =  0.25 M

Answer:

A. steel spoon

Explanation:

A steel spoon will get hot the quickest from the different given spoon. This is because steel is predominantly made up of a metal which shows metallic properties such as heat conduction.

Other properties originating from metallic bonds are ductility, malleability, luster etc.  

Answer:

when infectious agents get into the human body your body responds by raising the core body temperature causing a fever

The answer is C it will raise your body temp and cause a fever

Answer:

29.9 moles

2C²H¹⁰ needs 13 moles of O²

4.6 C⁴H¹⁰ needs X moles of O²

X= 13× 4.6 ÷ 2 = 59.8 ÷ 2 = 29.9 moles

29.9 moles of O2 are required to react completely with 4.6 mol of C4H10.

2C²H¹⁰ needs 13 moles of O²

4.6 C⁴H¹⁰ needs x moles of O²

x= 13× 4.6 ÷ 2

= 59.8 ÷ 2

= 29.9 moles

A mole is described as the quantity of a substance that contains exactly 6.02214076 X1023 primary entities of the given substance. as a result, a mole of a substance is referred to as the mass of a substance containing the equal wide variety of essential gadgets as atoms in exactly 12.000 g of 12C.

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mass Zn : 4.77 g

mass HCl : 5.32 g

The reaction equation is the chemical formula of reagents and product substances

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.

Reaction

[tex]\tt Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]

MW ZnCl₂=136,286 g/mol

[tex]\tt mol=\dfrac{10}{136.286}=0.073[/tex]

mol Zn : mol ZnCl₂ = 0.073

mass Zn :

[tex]\tt 0.073\times 65,38=4.77~g[/tex]

mol ZnCl₂ : mol HCl = 1 : 2

mol HCl :

[tex]\tt 0.073\times 2=0.146[/tex]

mas HCl :

[tex]\tt 0.146\times 36,46=5.32~g[/tex]

1. HNO₃ (g) + 4H₂ (g) ⇒ NH₃ (g) + 3H₂O (g)

2. Exothermic.

3. 2293.2 kJ

Reaction

HNO₃ (g) + H₂ (g) ⇒ NH₃ (g) + H₂O (g) △H = −637 kJ

1. Balance

give coefficient :

HNO₃ (g) + aH₂ (g) ⇒ bNH₃ (g) + cH₂O (g)

H, left=1+2a, right=3b+2c⇒1+2a=3b+2c(eq 1)

N,left=1, right=b⇒b=1

O,left=3, right=c⇒c=3

eq 1 : 1+2a=3.1+2.3⇒1+2a=9⇒2a=8⇒a=4

Balance reaction :

HNO₃ (g) + 4H₂ (g) ⇒ NH₃ (g) + 3H₂O (g)

2.  exothermic⇒release heat(negative sign)

3. heat released :

mol H₂ :

[tex]\tt mol~H_2=\dfrac{7.2}{2}=3.6[/tex]

heat released :

[tex]\tt -637\times 3.6=-2293.2~kJ[/tex]

Answer:

CH3-CH2-CH2-CH2-CH2-OH. (1-PENTANOL)

Explanation:

The given compound is Pente-1-ne

Hydroboration oxidation reagent - BH3 +H2O2 + OH-

The reaction is initiated by boron hydride which attacks the terminal carbon because the middle carbon + charge will be stabilized by +I effect of the parent carbon chain. This similar process will happen thrice and all the hydrogens of Boron hydride will be lost and carbon chain of Pent-1-ene will be attached to boron and it will form TRIPENTYL BORANE, Then we will add H2O2+ OH- and finally OH- will be attached to the parent carbon chain and

1-PENTANOL will be formed.

CH3-CH2-CH2-CH=CH2 + HBO → CH3-CH2-CH2-CH2-CH2-OH

                                                               1-PENTANOL

Answer:

2.273M

Explanation:

What is the definition of molarity.

M = mols/L. So that's what we need to determine.

How much does a L weigh? That's

1.114 g/mL x 1000 mL = 1114 grams. Simple enough, eh?

How much of that 1114 g is H3PO4. It says it is 20% by mass, therefore, 1114 g x 0.20 = 222.8 g.

How many mols are there in 222.8 g H3PO4? That's mools = grams/molar mass = 222.8/98 = 2.273 mols.

The definition of M is what? M = mols/L. And you have 2.273 mol/L; that must be the molarity.

The formula is

density g/mL x 1000 mL x mass% x (1/molar mass) = M

1.114 x 1000 x 0.20 x (1/98) = 2.273 M.

Answer:

1 M

Explanation:

The molarity of a solution, M, is a measure of the concentration of that solution and it refers to the number of moles of solute (mol) per liter (L) of solution. The molarity (M) can be calculated using the formula:

M = number of moles (n) /volume (V)

In this question, a 500 ml aqueous solution of Na3PO4 was prepared using 82g of the solute.

Molar mass of Na3PO4 = 23(3) + 15 + 16(4)

= 69 + 31 + 64

= 164g/mol

Mole = mass/molar mass

mole = 82/164

mole = 0.5 mol

Volume in Litres (L) = 500 ml ÷ 1000 = 0.500L

Therefore, Molarity (M) = 0.5/0.500

Molarity = 1 M or 1 mol/L

The molarity of the solution is 1 M

From the question,

We are to determine the molarity of the solution.

First, we will determine the number of moles of the solute (Na₃PO₄) present

Mass of Na₃PO₄ = 82 g

Using the formula

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

Molar mass of Na₃PO₄ = 163.94 g/mol

∴ Number of moles of Na₃PO₄ present = [tex]\frac{82}{163.94}[/tex]

Number of moles of Na₃PO₄ present = 0.500 moles

Now, for the molarity of the solution

Using the formula

[tex]Molarity = \frac{Number\ of\ moles}{Volume}[/tex]

Volume of the solution = 500 mL = 0.5 L

∴ Molarity of the solution = [tex]\frac{0.500}{0.5}[/tex]

Molarity of the solution = 1 M

Hence, the molarity of the solution is 1 M

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Answer:

Increases

Explanation:

Atomic size is the amount of space between the nucleus of an atom and the outermost electron. So, as each additional energy level is added, the overall amount of space between the nucleus and the outermost electron increases because there is now an extra shell of electrons that is farther out.

Answer:

There will be no observed impact of adding twice as much Na2CO3 on the product

Explanation:

Stoichiometry gives the relationship between reactants and products in terms of mass, mole and volume.

If we consider the stoichiometry of the reaction, we will discover that the reaction occurs in a 1:1 ratio. This implies that use of twice the amount of Na2CO3 will only lead to an excess of Na2CO3 making the other reactant the limiting reactant. Once the other reactant is used up, the reaction quenches.

Hence, use of twice as much Na2CO3 has no impact on the quantity of product produced.

Answer:

answer C) 1 and 4

Explanation:

Answer:

C) 1 and 4

Explanation:

I took the test. Hope this helps!

Answer:

when the numbers are very large or very small

Explanation:

good luck