What volume of 12M HCI is needed to prepare 250
of 0.20M HCI?

The heat that is released by the combustion of 3.5 moles of methane is 3115 kJ/mol.

A thermochemical equation is a reaction equation that incorporates the amount of heat lost/gained.

In this case, the reaction equation is; CH4 + O2 ----->CO2 + 2H2O dH = -890 kJ/mol

If 1 mole of methane releases 890 kJ/mol

3.5 moles of methane will release 3.5 moles * 890 kJ/mol/1 mole

= 3115 kJ/mol

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Answer:

since water boil at 100 °C .so 500gof water Will still boil at 100 °C

The weather station is a place which contain instrument that collect data of atmospheric pressure, wind, humidity, etc to forecast weather. The weather station is powered by solar power.

A weather station is a place that measure atmospheric conditions, on the basis of temp., pressure, wind speed, etc conditions.

They can be based either in land or sea. They are necessary to forecast any disaster, so we can prepare for the disaster.

Thus, the weather station is a place which contain instrument that collect data of atmospheric pressure, wind, humidity, etc to forecast weather. The weather station is powered by solar power.

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Answer:

c. one must have a higher kinetic energy than the other system

Answer:

1.90 M

Explanation:

To find the molarity of the solution, you need to use the molarity equation. This formula looks like this:

Molarity (M) = moles / volume (L)

To use this equation, you need to perform some conversions. You should (1) convert mL to L (by dividing by 1,000), then (2) convert grams NaNO₃ to moles (via molar mass), then (3) plug moles and volume into the molarity equation.

155 mL / 1,000 = 0.155 L

25.0 g NaNO₃           1 mole
---------------------  x  -----------------  = 0.294 moles NaNO₃
                                  85.0 g

Molarity = moles / volume

Molarity = 0.294 moles / 0.155 L

Molarity = 1.8975....

Molarity = 1.90 M

5.1434 contains 5 significant figures and 4 decimals.

All zeros that occur between any two non-zero digits are significant. For example, 108.0097 contains seven significant digits.

Calculation:

5.1234 + 0.033÷ 1.650 = 5.1434

5.1434 contains 5 significant figures and 4 decimals. 5.1434 rounded to 4 sig figs is 5.143, to 3 sig figs is 5.14, and to 2 sig figs is 5.1.

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Answer:

10.41 g

Explanation:

ml and   cm^3   are generally interchangeable

15 cm^3     *   . 694  g/cm^3 =  10.41 g

Answer:

1,063 grams H₃PO₄

Explanation:

To find the mass of phosphoric acid (H₃PO₄), you should (1) convert molecules to moles (via Avogadro's number) and then (2) convert moles to grams (via molar mass from periodic table).

Molar Mass (H₃PO₄): 3(1.008 g/mol) + 30.974 g/mol + 4(15.998 g/mol)

Molar Mas (H₃PO₄): 97.99 g/mol

6.534 x 10²⁴ molecules H₃PO₄                       1 mole                         97.99 g
---------------------------------------------  x  -------------------------------------  x  --------------
                                                            6.022 x 10²³ molecules          1 mole

= 1,063 grams H₃PO₄

Answer:

need more info

Explanation:

i think so we need more info

The AH for the reaction is -137 kJ

Enthalpy of formation is the energy required by reactants to convert into products . It value can be positive or negative depending on the type of reaction, Endothermic or Exothermic.

In the question 3 step reaction is given

C₂H4 (g) + 3 O₂ (g) → 2 CO₂ (g) + 2 H₂O (1)   AH = - 1411. KJ

2 C₂H6 (g) + 7 O₂ (g) → 4 CO₂ (g) + 6 H₂O (1)   AH = - 3120. KJ

2 H₂ (g) + O₂ (g) → 2 H₂O (1)     AH = -571.6 kJ

To determine the enthalpy of formation for

C₂H4 (9) + H₂ (9)→ C₂H6 (g)

Adding reaction 1 and (1/2) 3 will give

C₂H4 (g) + 7/2 O₂ (g) + H₂ (g) ----> 2 CO₂ (g) + 3H₂O AH = -1696.8

For the second reaction

We will reverse the reaction and multiply it by 1/2

2 CO₂ (g) + 3 H₂O (1) -->  C₂H6 (g) + 7/2 O₂ (g)  AH = +1560

Adding the two new reactions.

C₂H4 (9) + H₂ (9)→ C₂H6 (g)    AH = -137 kJ

Therefore The AH for the reaction is -137 kJ

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Refraction is caused due to the change in speed of light when it enters from one medium to another. Hence, option B is correct.

Refraction happens when light changes direction, or bends when it moves from one material to another.

The cause of the refraction of light is that light travels at different speeds in different media.

This change in the speed of light when it moves from one medium to another causes it to bend.

Thus, refraction is caused due to the change in speed of light when it enters from one medium to another. Hence, option B is correct.

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Answer:

2H2O+O2-2H2O2

Explanation:

TO BALANCE equation both side should be equal

The molecular formula of the compound is C₄H₈O₄.

The molecular formula is the exact whole number ratio of the compound's elements. The empirical formula, as well as the molecular mass, are combined to generate the molecular formula.

Let's assume that the compound contains:

The empirical formula of the compound is:

C               H           O

40.6/12    5.1/1         54.2/16

3.38          5.1           3.38

Divide by the smallest value

3.38/3.38  5.1/3.38  3.38/3.38

1                  1.5≅ 2       1

= C₁H₂O₁

The empirical formula weight = (1 × 12) + (2 × 1) + (1 × 16)

The empirical formula weight = 30 g/mol

Molecular formula = (118.084 g/mol)/30 g/mol

Molecular formula = 3.94 ≅ 4

Therefore, the molecular formula for the compound is C₄H₈O₄.

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The relation between the volume and the pressure of the gas can be given by the ideal gas equation. Warm air has more volume and low pressure that makes them rise above the equator.

Pressure present and exerted by the atmospheric gases are called atmospheric pressure. The volume of the gas is in inverse relation to the pressure of the gas.

Warm air has a high volume compared to cold air. More volume results in low pressure making them rise above the dense layer of the equator region.

Therefore, the warm air rises due to a decrease in pressure.

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The statement that describes what makes a base weak is that the base will be unable to dissociate completely in water.

A base is any of a class of generally water-soluble compounds, having bitter taste, that turn red litmus blue, and react with acids to form salts.

Bases usually dissociate into hydroxide ions (OH-) when in an aqueous solution.

However, a base is termed weak or strong depending on it's ability to dissociate completely. A weak base does not dissociate completely into hydroxide ions when in an aqueous solution.

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Answer:

When sodium metal is dropped in water, hydrogen gas is evolved. Thus, the reaction is, 2Na+2H2O→H2+2NaOH. In the reaction, sodium hydroxide is formed and hydrogen gas is evolved.

Explanation:

The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.

The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is calculated as follows;

H₂CO3 ⇄ 2H⁺  + CO₃²⁻

x         :      2x        x

ksp = (2x)²x

ksp = 4x³

(1.8 x 10⁻¹⁴) = 4x³

(1.8 x 10⁻¹⁴) /4 = x³

4.5 x 10⁻¹⁵ = x³

x = (4.5 x 10⁻¹⁵)^¹/₃

x = 1.65 x 10⁻⁵ mol/dm³

Thus, the equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.

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The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.

Solubility is defined as the maximum amount of a substance that will dissolve in a given amount of solvent at a specified temperature.

The equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is calculated as follows;

H₂CO3 ⇄ 2H⁺  + CO₃²⁻

x         :      2x        x

ksp = (2x)²x

ksp = 4x³

(1.8 x 10⁻¹⁴) = 4x³

(1.8 x 10⁻¹⁴) /4 = x³

4.5 x 10⁻¹⁵ = x³

x = [tex](4.5 X 10^{-15})^{\frac{1}{3} }[/tex]

x = 1.65 x 10⁻⁵ mol/dm³

Thus, the equilibrium solubility of cadmium carbonate in a solution at constant pH of 11 is 1.65 x 10⁻⁵ mol/dm³.

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About 80g of KCl will dissolve in 200g of water at 50 degrees.

A saturated solution contains just as must solute as it can normally hold at a given temperature.

Looking at the table we can see that about 40 g of KCl dissolves in 100 g of water at 50 degrees hence about 80g of KCl will dissolve in 200g of water at 50 degrees.

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Answer:

4.87 g

Explanation:

The formula between the number of moles, mass and Mr can be used to find the mass of barium.

Number of moles = mass ÷ Mr

So, mass = number of moles × Mr

  Mr of Ba = 137.3

∴ Mass = (3.55 × 10⁻²)  × 137.3 = 4.87 g

Answer:

Discussion: Red cabbage is useful as a pH indicator because the leaves contain a pigment molecule from the family of anthocyanins (shown below) which are responsible for many of the red/purple/blue colors observed in fruits and vegetables. In neutral solutions, the color observed is purple.

hope this helps:3

By convention, the standard enthalpy of formation of all elements in their standard states are assumed to be zero. Here the enthalpy value for the intermediate formation step is  -572 kJ. The correct option is D.

The standard enthalpy of formation of a compound is defined as the enthalpy change accompanying the formation of one mole of the compound from its constituent elements, all the substances being in their standard states.

The symbol used to represent the standard enthalpy of formation is ΔfH⁰.  The knowledge of standard enthalpies of various substances is useful for calculating the standard enthalpies of a reaction.

The overall energy difference between the reactants and products remains the same no matter how many intermediates there are in the reaction pathway.

The enthalpy value  = 2 × -286 = -572 kJ

Thus the correct option is D.

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From the calculations, the equilibrium constant of the reaction is given as   0.050

The term equilibrium constant refers to the number that shows the extent to which reactants are converted into products.

The equilibrium constant of this reaction can be obtained from;

K = [0.050] [1.00]^4

K = 0.050

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When investigative officers get to a crime scene, they do not need to collect water samples.

A crime scene is a place where an offence has been committed. It is usually cordoned off to enable investigation of the crime and the collection of samples.

When investigative officers get to a crime scene, they do not need to collect water samples.

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Answer:A

Explanation:.

Answer:

Burning of paper and log of wood.

Digestion of food.

Boiling an egg.

Explanation:

Answer:

 hydrogen gas will occupy 0.0374 liters when is cooled to 83 °C.

Explanation:

• T1 =602 °C = 875 K

• V1 =92 mL = 0.092 L

0.092L/875K= 1.05×10-⁴L/K

vf =nR/P T f= 1.05×10-⁴L/K ×356K

=0.0374 L

Answer:

0.0315 moles CH₂OH

Explanation:

You can find the amount of moles using the molarity equation. This equation looks like this:

Molarity (M) = moles / volume (L)

Once you convert mL to L (by dividing by 1,000), you can plug the molarity and volume into the equation and isolate to find moles. The final answer should have 3 sig figs because the given value with the lowest amount of sig figs (0.210 M) has this amount.

150.0 mL / 1,000 = 0.1500 L

Molarity = moles / volume

0.210 M = moles / 0.1500 L

(0.210 M x 0.1500 L) = moles

0.0315 = moles

Answer:

Copper (Cu2) , Iron (Fe2+ Fe3 +) , and Hydrogen ion (H+)

Explanation:

I hope it helps u dear! ^_^