A certain atom contains 53 protons, 78 neutrons, and 54 electrons. What is the mass number of this atom?.

By using the data given in the text and the specific heat capacity of water and its density, we can calculate that the amount of heat produced by hydrocarbon combustion was 233.6 kJ.

The heat released by hydrocarbon combustion is absorbed by the calorimeter and the water in it. To calculate the amount of heat (Q) produced by the combustion, we are going to use the specific heat capacity of water (c = 4.186 J/g°C), the heat capacity of the calorimeter (q = 68.5 J/°C) and the difference in temperature (ΔT = 54.91 °C):

heat absorbed by the calorimeter = ΔT*q

heat absorbed by water = ΔT*c*m

Q = ΔT*q + ΔT*c*m

m - the mass of water

To obtain the mass of water, we are going to use the volume (V = 1000 mL) of water and its density (d = 1.00 g/mL):

d = m/V ⇒ m = d * V

m = 1.00 g/mL * 1000 mL

m = 1000 g

Now we can plug all the known values in the formula for Q:

Q = 54.91 °C * 68.5 J/°C + 54.91 °C * 4.186 J/g°C * 1000 g

Q = 233,614.595 J

Q = 233.6 kJ

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Answer:

Explanation:

so

1.5 atm pressure will be required for neon at 30°C to have the same density as nitrogen at 20°C and 1.0 atm.

The relationship between a gas's pressure P, volume V, and temperature T in the range of low pressures and high temperatures, when the gas's molecules move virtually independently of one another, is known as the ideal gas law, also known as the perfect gas law.

T[tex]_N_e[/tex]​ =30⁰C=(30+273)K=303K

T[tex]_N_2[/tex]​​ =20⁰C=(20+273)K=293K

P[tex]_N_2[/tex] ​ =1.0atm

Ideal gas constant - R=0.0821L⋅atm/ K⋅ mol

The molar mass of

Neon - M[tex]_N_e[/tex]​​=20.18g/mol

Nitrogen - M[tex]_N_2[/tex]​​ ​ =2⋅14.007g/mol=28.014g/mol

Determine the pressure P[tex]_N_e[/tex]​  required for neon at 30⁰C to have the same density (d) as nitrogen at 20⁰C.

d = m/V

We know that

n = m/M

Using the ideal gas law, we get

PV = nRT

PV = m/M *RT

Since

PM/RT = m/V =d

d =  PM/RT

d= [tex]\frac{P_{N_2} M_{N_2}}{R T_{N_2}}[/tex]

d = 1.0 atm * 28.014 g/mol/0.0821L atm/K mol 293K

d = 1.2 g//L

Since both gases have the same density, we can calculate the pressure of neon gas, using

[tex]d=\frac{P_{N e} M_{N e}}{R T_{N e}}[/tex]

[tex]P_{N e}=\frac{d R T_{N e}}{M_{N e}}[/tex]

[tex]P_{N e}[/tex]=1.2g/L . 0.0821L . atm/K.mol.303 K/20.18 g/mol

[tex]P_{N e}[/tex]=1.5 atm

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Answer:

Explanation:

To find the number of entities in a given substance we use the formula

N = n × L

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question

n = 2.5 moles

We have

N = 2.5 × 6.02 × 10²³ = 1.505 × 10²⁴

We have the final answer as

Hope this helps you

Answer:

C. high ionization energy and high electronegativity

Explanation:

When an electron is gained or lost from an atom or a molecule, an ion is formed. When a molecule or atom gains electrons, anions (which are negatively charged ions) are formed.

The following two statements are true about chemical kinetics.

1. Chemical  kinetics is the study of the rate of reactions.
2. A reaction rate can be defined as the decrease in the concentrations of reactants with time.

Chemical kinetics deals with the study of rate of chemical reactions. Rate of reaction is defined as  the measure of the change in concentration of the reactants or the change in concentration of the products per unit time.

The reaction rates decrease with time because reactant concentrations decrease as reactants are converted to products. The rate decreases as the reaction proceeds.

               A→B

A= reactant        rate of reaction =-[tex]\frac{d[A]}{dt}[/tex]

B=product          rate of reaction=+[tex]\frac{d[B]}{dt}[/tex]

This means that the concentration of 'A' decrease  with respect to time. It can also be noted by measuring the increase in the Concentration of B with the passage of time.

Negative sign indicates the conc. of reactants decreases with time

Positive sign indicates that conc. of product increases with the passage of time .Remember rate of reaction always positive.

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The release of O₂( oxygen) from the process of photosynthesis is what made them to be able to float.

This is referred to as the process in which green plants manufacture their food in the presence of sunlight which is trapped by chlorophyll.They are known as primary producers and they use compounds such as water and carbondioxide.

The reactants mentioned above undergo series of reactions which leads to the production of glucose and oxygen is given off as a result which is the element responsible for the floating of the aspirated spinach leaf disks in this scenario.

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The list that consists of elements that have the most similar chemical properties is caesium, sodium and potassium (option D).

Periodic table is the tabular chart of the chemical elements according to their atomic numbers so that elements with similar properties are in the same group (column).

The periodic table is made up of chemical elements arranged in groups and periods. Chemical elements in the same group possess similar chemical properties.

According to this question, the following elements are in the same group 1:

Therefore, Cs, K and Na will have the most similar chemical properties because they belong to the same group.

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The strong attractive forces in ionic crystal make them rigid , hard and brittle solid.

Ionic crystal are so strong because of the strong attractive forces between ions . Ionic compound formed between a positively charged ion and a negatively charged ion , the bond between them are so strong that make ionic crystal brittle. and also make it rigid.  the presence of strong electrostatic force of attraction make the ionic crystal so hard. Due to the non directional nature of ionic bond make the crystal brittle.

Thus, The strong attractive forces in ionic crystal make them rigid , hard and brittle solid.

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The true statement about Matter is that matter is anything that is made up of atoms and that has mass.

Matter is anything which is made up of mass and that has mass. and that occupies space.

If we talk about space, there is no matter because there is nothing but vacuum.

Matter is a general terms given to a group of atoms or molecules which are taken in a general.

We all are made up of atoms, because we al have mass and we all occupy some space. The same goes to anything that we can see or touch or feel that it exist.

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Answer: Matter is anything that is made of atoms and that has mass.

Explanation: I took the test.

A total of 2269 balloons of 1.5 Liters volume and 1.25 atm pressure can be filled from the cylinder of volume 2.3 Liters and 1850 atm pressure.

The volume of the Helium gas is 2.3L and the pressure is 1850 atm at 25° Celsius.

The smaller balloons that has to be filled are of volume 1.5 L at the pressure 1.25atm at the same temperature of 25° C.

Because the temperature is conserved, so, according to Boyle's law,

When temperature is constant, the pressure and volume of the gas are inversely proportional to each other.

we can write,

P₁V₁ = P₂V₂

Let us say that a total n numbers of smaller balloons can be filled, so,

P₁V₁ = n(P₂V₂)

Where,

P₁ is pressure of bigger balloon,

V₁ is the volume of the bigger balloon,

P₂ is the pressure of the smaller balloon and,

V₂ is the volume of the smaller balloon.

Now, putting all the values,

2.30 x 1850 = n(1.5 x 1.25)

n = 2269

So, a total 2269 balloons can be filled from the bigger balloon to the smaller balloons.

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Answer C I think

Explanation:

Answer:

HS is stripped from each O.

You should develop the TLC (thin layer chromatography) plate orthogonally (under a 90-degree angle) to the original direction of development (along its width, while the original development was along the length of the TLC plate).

This technique is called 2D TLC (two-dimensional thin layer chromatography) and is usually employed to analyze and preparatively separate very complex mixtures that cannot be separated using only one solvent system. The initial development (along the length of the TLC plate) enables crude separation into groups of compounds with similar retention factor (Rf). These groups can then be further separated using a different solvent system by developing the same TLC plate along its width.

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Answer:

Gold

Explanation:

To recognize what element this is, we can simply look at the last orbital (5d9) and go to the periodic table and see what element is in that final orbital.

We go to row 6 (because of the 6s orbital at the beginning of this row) and then we see that our 6s orbital is full with 2 electrons, then our 4f orbital is full with 14 electrons, and our 5d orbital is not full where we only have 9 electrons instead of 10.

We then go to our 5d orbital and count 9 times into that orbital and end up with our final element being Gold (Au).

The value into kilocalories up to three significant figures is 77.1 x 10^3 kilocalories

1 kj = 0.239 kilocalorie

3.23 x 10^6 kJ x 0.239 kilocalorie = 77.1 x 10^3 kilocalories

3.23 x 10^6 kJ = 77.1 x 10^3 kilocalories

In chemistry, Significant figures are the digits of value which carry meaning towards the resolution of the measurement. They are also called significant figures in chemistry. All the experimental measurements have some kind of uncertainty associated with them.

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Ba(OH)2(aq) + 2HNO3(aq) ==> 2H2O(l) + Ba(NO3)2(aq)  ...  balanced equation

A chemical equation that is balanced has the same number of each type of atom on both sides of the equation. Subscripts are a component of the chemical formulas for the reactants and products that show how many atoms of the previous element there are in each.

note the stoichiometry ...  2 mols HNO3 for each 1 mol Ba(OH)2

Now we can use dimensional analysis and the noted stoichiometry to solve the problem:

32.0 ml HNO3 x 1 L/1000 ml x 0.200 mol / L = 0.0064 mols HNO3 used

0.0064 mol HNO3 x 1 mol Ba(OH)2 / 2 mols HNO3 = 0.0032 mol Ba(OH)2 present

Concentration of Ba(OH)2 = mols/L = 0.0032 mols / 0.0250 L = 0.128 M

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The mass number of this atom having 53 protons, 78 neutrons, and 54 electrons will be 131.

In the field of science, we can describe a mass number of an atom as simply a measure of the protons and neutrons that are to be found in the nucleus of an atom. In chemistry, the mass number is denoted by the letter 'A'.

In the above-mentioned case, the number of protons of the atom is 53 whereas the number of neutrons is 78.

In order to calculate the mass number, we will add the number of protons and neutrons. As the result of the addition of 53+78 is 131 hence, the mass number will be 131.

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Using the percentage by volume of the solutions given, we can calculate that we require 216 mL of 100% alcohol and 384 mL of 50% alcohol.

The percentages given refer to the percentage by volume (%V). We need to make 600 mL of 68% alcohol solution, by mixing a certain volume of 50% solution (A) and a certain volume of 100% alcohol (B). So, we know that:

A + B = 600 mL

We also know that the total volume of alcohol in the end solution needs to be:

0.68 * 600 mL = 408 mL

So, by extension:

0.50 * A + B = 408 mL

Based on the first equation, we can say that:

A = 600 mL - B

If we use that A in the second equation we get:

0.50 * (600 mL - B) + B = 408 mL

300 mL - 0.50 B + B = 408 mL

If we rearrange this equation we get:

B - 0.50 * B = 408 mL - 300 mL

0.50 * B = 108 mL

B = 108 mL / 0.50

B = 216 mL

A = 600 mL - 216 mL = 384 mL

So, we need 216 mL of 100% alcohol and 384 mL of 50% alcohol solution to get 600 mL of 68% alcohol solution.

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Answer:216 ml

Explanation: I got it right

The mass of the iron oxide produced in the given chemical reaction is equal to 27.04 grams.

The limiting reagent in a chemical reaction can be described as that reactant that will decide the amount of the yield of the product. The reactant consumed first will confirm the completion of the reaction if the reactants are not taken in stoichiometry.

Given the chemical reaction of the formation of iron oxide:

4Fe   +    3O₂    →    2Fe₂O₃

Given the mass of the iron = 15.4 grams

The moles of the iron = 15.4/56 = 0.275 mol

The mass of the oxygen gas = 3.6 grams

The moles of the oxygen gas = 3.6 /32 = 0.1125 mol

From the chemical equation, 4 moles of the Fe react with oxygen = 3 mol

Then 0.275 mol of the Fe will react with oxygen = 3/4 × 0.275 = 0.206 mol

Therefore, oxygen is the limiting reagent here.

The 3 mols of oxygen produced iron oxide = 2 mol

0.1124 mol of oxygen will produce iron oxide = (2/3) × 0.1125 = 27.04 g

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Answer: True

Explanation: Synthetic materials are not found in nature and can be created in labs using chemicals and compounds.

The volume of Concentrated nitric acid (16 m) required to react with 0.41 g of cu(s) if you use 1.86 ml (an excess) of hno3, what volume of 5.0m naoh will need to neutralize completely dissolved is 0.704 ml

4 HNO3(l) + Cu(s) ==> Cu(NO3)2(s and aq) + 2 NO2(g) + 2 H2O(l)

According to net Ionic equation 4 moles of HNO3 reacts with 1 mole of Cu(s)

moles of Cu in 0.36 gm of Cu = 0.36/63.5

moles = molarity*volume(L)

moles of Cu*4 =moles of HNO3

Let volume of HNO3 be x

0.36/63.5*4 = 16*x

x = 1.42 ml

c. Volume of HNO3 added = 1.64 ml

excess of HNO3 = 1.64-1.42

= 0.22 ml

Normality of NaOH and HNO3 is same i.e. equal moles of NaOH and HNO3 neutralises itself

molarity of NaOH = 5 moles/litre

moles of NaOH = Moles Of HNO3

5*x = 16*0.22

x = 0.704 ml

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Answer:

the periodic table is the table of contents of the elements

First, we have to remember the law of conservation of matter:

"The matter can not be created nor destroyed. It can only be transformed".

Then, the answer, in theory, has to be 11.0 g, that is the addition of 5.0 g and 6.0 g.

The heat of reaction is  1.8 KJ. A calorimeter is a device used in calorimetry, a procedure for calculating heat capacity and measuring the heat of chemical processes or other physical changes.

Volume of water = 67.9 mL

Since the density of water is 1.00 g/mL

Density = mass/volume

Mass of water = Density × volume

Mass of water =  1 g/mL × 67.9 mL

Mass of water = 67.9g or 0.0679 Kg

Temperature change =  6.5 oC

Specific heat capacity of water= 4.184 J/Kg

From;

H = mcθ

m = mass of water

c = heat capacity of water

θ = temperature rise

Substituting values;

H = 0.0679 Kg × 4.184 J/Kg × 6.5 oC

H = 1.8 KJ

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Answer:

Explanation:

Here, we want to get which of the compounds have the highest percentage by mass of nitrogen

What we have to do here is to divide the mass of nitrogen atoms in the compound by the molecular mass of the compound

a) NH3

The atomic mass of nitrogen is 14 amu, the atomic mass of hydrogen is 1 amu

The molar mass is thus 14 + 3(1) = 17 g/mol

The percentage by mass of nitrogen will be

14/17 * 100 = 82.35 %

b) HCN

The atomic mass of carbon is 12 amu

Thus, we have the molar mass as

1 + 12 + 14 = 27 g/mol

Percentage of nitrogen by mass will be : 14/27 * 100 = 51.85 %

c) For N2O

The atomic mass of oxygen is 16 amu

The molar mass of the compound will be 14(2) + 16 = 44 g/mol

Percentage of nitrogen by mass will be = 28/44 * 100 = 63.64 %

d) NI3

The atomic mass of iodine is 127 g/mol

So the molar mass of the compound will be:

14 + 3(127) = 395 g/mol

Percentage by mass of nutrogen will be

14/395 * 100 = 3.54 %

From what we have, the highest percentage by mass of nitrogen is 82.35 % and that belongs to ammonia (NH3)