can anybody pls help me with chemistry how to balance an equation of class 7 ??? pls
really I don't like chemistry..
I need only the step(s)..

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Given is the ratio of conjugate base and conjugate acid of phosphoric acid. pH of a substance is the concentration of the hydrogen ions in its solution and higher this concentration lower is the value of pH.

pKa value is a measure of the strength of acid, it is the negative log of acid dissociation constant Ka.

Answer:

0.518 g

Explanation:

Step 1: Write the balanced equation

3 CaCl₂ + 2 H₃PO₄ ⇒ Ca₃(PO₄)₂ + 6 HCl

Step 2: Calculate the moles corresponding to 0.555 g of CaCl₂

The molar mass of CaCl₂ is 110.98 g/mol.

0.555 g × 1 mol/110.98 g = 5.00 × 10⁻³ mol

Step 3: Calculate the moles of Ca₃(PO₄)₂ produced

5.00 × 10⁻³ mol CaCl₂ × 1 mol Ca₃(PO₄)₂/3 mol CaCl₂ = 1.67 × 10⁻³ mol Ca₃(PO₄)₂

Step 4: Calculate the mass corresponding to 1.67 × 10⁻³ moles of Ca₃(PO₄)₂

The molar mass of Ca₃(PO₄)₂ is 310.18 g/mol.

1.67 × 10⁻³ mol × 310.18 g/mol = 0.518 g

Answer:

N 2 H4

Explanation:

Answer:

14

73%

Explanation:

The mean Number of years worked :

. (sum of service years) / employees in the

(8+13+15+3+13+28+4+12+4+26+29+3+10+3+17+13+15+15+23+13+12+1+14+14+17+16+7+27+18+24) /

(417 / 30)

= 13.9 years

= 14 years

The percentage of employees who have worked for atleast 10 years :

Number of employees with service years ≥ 10 years = 22 employees

Total number of employees

Percentage (%) = (22 / 30= * 100% = 0.7333 * 100% = 73.33% = 73%

Answer:

The most important difference between the two is that butter is derived from dairy and is rich in saturated fats, whereas margarine is made from plant oils. ... If the margarine contains partially hydrogenated oils, it will contain trans fat, even if the label claims that it has 0 g.

Explanation:

(⌒_⌒;)

Answer:

The hot water dissolves the flavor and color components.

Explanation:

Caffeine can be extracted from the tea leaves into hot water because the hot water dissolves the flavor and color components away from the solid vegetable. This is an example of a solid-liquid extraction. We can extracted the aqueous solution and isolated the crude caffeine by converting the components of caffeine into their calcium salts which are insoluble in water. Then the caffeine can be extracted from the water by using methylene chloride.

Answer:

heat; temperature; surrounding; insulated.

Explanation:

A calorimeter can be defined as a scientific instrument or device designed and developed for measuring the heat involved in reactions or other processes, especially by taking the measurement of the temperature of the materials surrounding the process.

Basically, a calorimeter is insulated using materials with very high level of resistivity so as to prevent heat transfer to the outside of the device (calorimeter). Some of the components that make up a simple calorimeter are thermometer, an interior styrofoam cup, an exterior styrofoam cup, cover, etc.

Additionally, a calorie refers to the amount of heat required to raise the temperature of a gram of water by one degree Celsius (°C).

Answer:

C. The enthalpy of the products is higher than that of the reactants

Explanation:

An endothermic process is any process with an increase in the enthalpy of the system

The enthalpy of the products is higher than that of the reactants describes an endothermic process. Therefore, option (C) is correct.

An endothermic process can be described as any thermodynamic process with an increase in the enthalpy H of the system. In such a process, a closed system commonly absorbs thermal energy from its surroundings.

An endothermic reaction leads to an increase in the temperature of the system and a decrease temperature of the surroundings. A physical process, such as the melting of ice cubes is an endothermic process.

Whether a process can take place spontaneously depends not only on the enthalpy change but also on the entropy change and absolute temperature.

An endothermic process commonly needs a favorable entropy increase  (∆S > 0) in the system. In an endothermic process, the energy of the products is higher than that of the reactants.

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Answer:

The choose ( D )

weak interactions between molecules.

Answer:

Explanation:

el     a  

Answer:

Yes because same topic are long

Answer:

e−(Ea/RT): the fraction of the molecules present in a gas which have energies equal to or in excess of activation energy at a particular temperature

Answer:

D. Temperature and activation energy is the correct answer

Explanation:

^_^

Answer:

Volume of hot water required = 3.85L

Explanation:

Suppose volume of hot Then volume of water required cold water = = x L (10.0-x) L

Heat given by hot water (Q₁)

= mass of hot water x heat capacity of water X AT

= x L * 4.184 * J / g. к x(61.0-37.0) °℃.

And Heat absorbed by cold water (Q₂) = (10.0-x) L x 4.184 J/g*k x(37+0 -220) C

Since energy is consumed, Q₁ = Q2.

i.e. X*l *4.184*J/g*k*24C = (10.0-x)L x 184 5

24 x 15 (10.0-x) = 150. - 15x

x = 150. (24+15) = 3.846

So, volume of hot water required. = 3.85 L

When the temperature of the water increases the water becomes hot.

According to the question the volume of hot water required = 3.85L.

Suppose volume of hot Then the volume of water required cold water  is [tex]x L (10.0-x) L[/tex]

All the data are given in the question, which is as follows:-

The formula we are going to use is as follows:-

= mass of hot water x heat capacity of water X AT

= [tex]x L * 4.184 *(61.0-37.0) ^oC[/tex]

The heat absorbed by cold water (Q₂) = [tex](10.0-x) L *4.184 *(37+0 -220) ^oC[/tex]

Since energy is consumed, Q₁ = Q2.

[tex]X*l *4.18424C = (10.0-x)L * 184 524 * 15 (10.0-x) = 150. - 15xx = 150. (24+15) = 3.846[/tex]

Hence, the volume of hot water required is = 3.85 L

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Answer:

hope it helps much as you can

Answer:

heating of gases depends not only on the temperature difference, but also on the process as well as the amount of gas present.

Explanation:

The work done when a gas is heated does not only depends on the initial and final states of the gas but also on the process used to achieve the change of state of the gas.

Several processes can be applied in changing the state of a gas such as; adiabatic process, isobaric process, isochoric process and isothermal process.

Hence, the heating of a gas, depends not only on the temperature difference, as well as the amount of gas present according to the ideal gas laws but also on the process used to achieve the change of state.

Answer:

If the gas is at STP, THE 1 mole is 22.4 liters.

Explanation:

Answer:

acetaldehyde

When acetaldehyde is heated with Fehling's solution, a red precipitate is formed.

Explanation:

Answer:

pH=8.676

Explanation:

Given:

0.75 M [tex]NH_{3}[/tex]

0.20 M [tex]NH_{4}[/tex]

The objective is to calculate the pH of the buffer using the kb for [tex]NH_3[/tex]

Formula used:

[tex]pOH=pka+log\frac{[salt]}{[base]}\\[/tex]

pH=14-pOH

Solution:

On substituting salt=0.75 and base=0.20 in the formula

[tex]pOH=-log(1.77*10^{-5})+log\frac{0.75}{0.20}\\ =4.75+0.5740\\ =5.324[/tex]

pH=14-pOH

On substituting the pOH value in the above expression,

pH=14-5.324

Therefore,

pH=8.676

Answer:

It is equal to the total mass of the products.

Explanation:

Hope this helps :)

Answer:

B. False

Explanation:

Water does NOT react too copper. Copper does not react with water because the oxygen in water is locked into a compound with one part oxygen and two parts hydrogen. Copper oxide is a compound from the two elements copper and oxygen. Everything else listed does but since water is on this list it is false.

Answer:

Explanation:

First we convert the given masses into moles, using the compounds' respective molar mass:

Then we multiply each amount by Avogadro's number, to calculate the number of molecules:

Answer:

1. Vacuole

2. chloroplast

3. Nucleus

4. Plasma membrane - cell membrane

5. Vacuole (same as #1 ?) could be vesicle

Explanation:

Answer:

25.08 grams of O₂ are needed to react with 8.15 g of C₂H₂.

Explanation:

The balanced reaction is:

2 C₂H₂ + 5 O₂ → 4 CO₂ + 2 H₂O

By reaction stoichiometry, the following amounts of moles of each compound participate in the reaction:

The molar mass of each compound is:

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

Then you can apply the following rule of three: if by stoichiometry 52 grams of C₂H₂ react with 160 grams of O₂, 8.15 grams of C₂H₂ react with how much mass of O₂?

[tex]mass of O_{2} =\frac{8.15 grams of C_{2} H_{2}*160 grams of O_{2} }{52 grams of C_{2} H_{2}}[/tex]

mass of O₂= 25.08 grams

25.08 grams of O₂ are needed to react with 8.15 g of C₂H₂.

Answer:

D

Explanation:

The longer handles distribute the force across a longer distance.

Answer:

B

Explanation:

Spontaneous in chemical reactions means without any external input.

Occurring without added energy. Hence, option B is correct.

A spontaneous reaction is a reaction that supports the formation of products under the conditions under which the reaction is happening.

Spontaneous Reaction- a reaction that favours the formation of products at the conditions under which the reaction is occurring.

A non-spontaneous reaction can be made spontaneous if it is inside a controlled environment, this is what happens in nuclear power plants that create atomic fusion and fission in chambers that are controlled to control different particles to create nuclear active rays.

Hence, option B is correct.

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Answer:

104.8 g

Explanation:

From the question given above, the following data were obtained:

Initial temperature of copper (T꜀) = 275.1 °C

Mass of water (Mᵥᵥ) = 272 g

Initial temperature of water (Tᵥᵥ) = 21 °C

Equilibrium temperature (Tₑ) = 29.7 °C

Mass of copper (M꜀) =?

NOTE:

Specific heat capacity of copper (C꜀) = 0.385 J/gºC

Specific heat capacity of water (Cᵥᵥ) = 4.184 J/gºC

Finally, we shall determine the mass of the copper in the sample. This can be obtained as follow:

Heat loss by copper = Heat gained by water

M꜀C꜀(T꜀ – Tₑ) = MᵥᵥCᵥᵥ(Tₑ – Tᵥᵥ)

M꜀ × 0.385 (275.1 – 29.7) = 272 × 4.184(29.7 – 21)

M꜀ × 0.385 × 245.4 = 1138.048 × 8.7

M꜀ × 94.479 = 9901.0176

Divide both side by 94.479

M꜀ = 9901.0176 / 94.479

M꜀ = 104.8 g

Thus, the mass of the copper in the sample is 104.8 g

Answer:

Explanation:

Sample Response: If global warming continues, corals will continue to expel the algae from their cells to avoid poisonous buildup. This will cause corals to die. Without corals, the algae are not protected and cannot perform photosynthesis. This will cause the algae to die as well.

Answer:

False

Explanation:

An object with a density greater than 1.00g/mL (greater than the density of water) will sink. An object with a density less than the density of water, will float.

If the water has a density of 1.00 g/mL. If you put an object that has a density of 0.79 g/mL into water, it will sink to the bottom, this statement is false.

The density of an actual content is its mass per unit volume. The most common symbol for density is d, but the Latin letter D can also be used.

Three of an object's most fundamental properties are mass, volume, and density. Mass describes how heavy something is, volume describes its size, and density is defined as mass divided by volume.

The density of something is a measure of how heavy it is in relation to its size. When an artifact is more dense than water, it plunges; when an object is less dense than water, it floats.

Density is a property of a substance that is independent of the amount of substance.

As in the given scenario, water is having density 1 g/mL and object in having density less then it so it will float on water.

Thus, the given statement is false as the material will not sink, rather it will float on water.

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Answer:

The correct option is A

Explanation:

Some amino acids, called glucogenic amino acids, when catabolized convert there carbon backbones to tricarboxylic acid (TCA) cycle intermediates. These intermediates can be subsequently metabolized into carbon dioxide and water with the release of ATP or the formation of glucose (known as gluconeogenesis.

All amino acids (with the exception of leucine and lysine) are glucogenic and can thus generate the carbon backbones required for gluconeogenesis. Thus, the correct option is a.

Answer:

1. Its formation requires very strong updrafts = a. Hail

2. Its formation requires falling through a layer of above-freezing air = d. Freezing Rain

3. Precipitation from cumuliform clouds is typically of this nature = c. Shower

4. Precipitation from stratus clouds is typically of this nature = Drizzle

Explanation:

Hail formation requires very strong updrafts, these updrafts are the upward moving air created in a thunderstorm. This period of noticeable thunderstorms creates hails.

Freezing rain requires the presence of warm air, it requires falling through a layer of above-freezing air to the colder air below to produce an ice coating on anything it drops on.

Showers are produced by cumuliform clouds which look like cotton balls. Since cumuliform clouds precipitate too, these clouds can have fluctuating rain in a day in the form of showers.

Drizzle which raises low visibility is considered a type of liquid precipitation since it also falls from a cloud. Drizzle which is obviously smaller in diameter when compared to that of raindrops, however, is common with stratus clouds.

Answer:

0.350 L

Explanation:

First we convert 2.18 g of Na₂O₂ into moles, using its molar mass:

Then we convert 0.0279 moles of Na₂O₂ into moles of O₂, using the stoichiometric coefficients of the reaction:

Finally we use the PV=nRT formula to calculate the volume of oxygen produced:

Inputting the data: