What are the two ways that humans lose heat? PLS help thank you!

Answer:

the 3rd one (0.01 cm the one selected already)

Explanation:

copper wire isn't excessively big, and it wraps around the pencil because its malleable. I think that the most accurate would be 0.01 cm

Answer:

0.77mol/Kg.

Explanation:

The following data were obtained from the question:

Mass of NaCl = 4.5g

Mass of water = 100g.

Molality =...?

Next, we shall determine the number of mole in 4.5g of NaCl. This can be obtained as follow:

Mass of NaCl = 4g.

Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

Number of mole NaCl =..?

Mole = Mass /Molar Mass

Number of mole of NaCl = 4.5/58.5

Number of mole of NaCl = 0.077 mole.

Next, we shall convert 100g of water to kilograms. This is illustrated below:

1000g = 1kg

Therefore, 100g = 100/1000 = 0.1Kg.

Finally, we can determine the molality of the solution as follow:

Molality is simply defined as the mole of solute per unit kilogram of solvent (water). Mathematically, it is represented as:

Molarity = mole of solute / kg of solvent

Mole of solute, NaCl = 0.077 mole

Kg of solvent = 0.1kg

Molality = 0.077mol/0.1kg

Molality = 0.77mol/Kg

The molarity of the solution is 0.77mol/Kg.

Since

Mass of NaCl = 4.5g

Mass of water = 100g.

Here,

Mass of NaCl = 4g.

Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

Now

Mole = Mass /Molar Mass

= 4.5/58.5

= 0.077 mole.

Now

1000g = 1kg

So,

100g = 100/1000 = 0.1Kg.

Now

Molarity = mole of solute / kg of solvent

Mole of solute, NaCl = 0.077 mole

Kg of solvent = 0.1kg

So,

Molality = 0.077mol/0.1kg

= 0.77mol/Kg

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Answer:

true

Explanation:

polarity of the molecules increased with electronegatiy it's true

Answer:

2H + O -------> H2O

and hydrogen react with oxygen so it is oxide of hydrogen

like iron react with Oxygen and give

iron oxide

Explanation:

after passing electric current in the water the two gases will get seperated and on bringing the matchstick close to hydrogen it will burn with a pop sound

Answer:

Replication

Explanation:

In science, the work of a scientist is regarded as authentic if other experts in other places can follow the same steps as he/she claimed to follow and arrive at the same result.

For example, a scientist in California, United States of America may carry out a research and publish his findings. Another scientist in Christchurch New Zealand following exactly the same procedure is expected to arrive at the same results as the original researcher if there were no errors in the work.

However, where there are disparities in results, the scientist in Newzealand may discover errors that were unknown to the original researcher in the united States. The New Zealand scientist was carrying out a process known as 'replication'. That is, repeating a scientific research in order to obtain the same results thereby validating the research.

Answer:

Because electronegativity of Oxygen is higher than electronegativity of Carbon.

Explanation:

The electrons in a bond between carbon and oxygen, C-O, closer to the oxygen atom than the carbon atom because electronegativity of Oxygen is higher than electronegativity of Carbon.

Answer: 2.5 grams

Explanation:

Expression for rate law for first order kinetics is given by:

[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]

where,

k = rate constant

t = age of sample

a = let initial amount of the reactant

a - x = amount left after decay process  

a) to calculate the rate constant:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]

[tex]k=\frac{0.693}{2years}=0.346years^{-1}[/tex]

b) to find amount left after 4 years

[tex]4=\frac{2.303}{0.346}\log\frac{10}{a-x}[/tex]

[tex](a-x)=2.5g[/tex]

Thus 2.5 g of cesium would remain from a 10 g sample after 4 years

Answer:

They all have the same number of molecules or atoms which is 3.011*10²⁴ molecules or atoms.

5 moles of O = 3.011*10²⁴ molecules or atoms

5 moles of N = 3.011*10²⁴ molecules or atoms

5 moles of MgCl2 = 3.011*10²⁴ molecules or atoms

5 moles of C2H3NO = 3.011*10²⁴ molecules or atoms.

Explanation:

a)

5 moles of O = ?

1 mole of any substance is equal to Avogadro's number which is equal to 6.022×10²³molecules or atoms

From the question above,

5 moles of O = 5 × 6.022*10²³ = 3.011×10²⁴atoms or molecules.

b)

5 moles of N

From the same principle or fundamentally stated fact above,

1 mole of any substance = 6.022*10²³molecules or atom

5 moles of N = 5 × 6.024

2*10²³ = 3.011*10²⁴atoms or molecules.

c)

5 moles of MgCl₂

Same principle we used in a and b,

1 mole of any substance = 6.022*10²³ atoms or molecules

5 moles of MgCl2 = 5.0×6.022*10²³ = 3.011*10²⁴ atoms or molecules.

d)

5 moles of C₂H₃NO = ?

1 mole of C₂H₃NO = 6.022*10²³molecules or atoms

5 moles = x molecules or atoms

x = 5 × 6.024

2*10²³ = 3.011*10²⁴ atoms or molecules

What this proves is that no matter the compound, molecule or element, as long as they have equal amount of moles, they'll have the same number of atoms, molecules or particles.

Answer:

a. 3.011x10²⁴ atoms of O in 5 moles.

b. 3.011x10²⁴ atoms of N in 5 moles.

c. 3.011x10²⁴ atoms of MgCl₂ in 5 moles.

d. 3.011x10²⁴ atoms of C₂H₃NO in 5 moles

Explanation:

A mole is defined as the number of atoms in exactly 12.000g of ¹²C.

This number is equal to 6.022x10²³. That means 1 mole is equal to 6.022x10²³.

Thus:

a. O . 5 moles of oxygen (An atom) are:

5 moles O ₓ (6.022x10²³ atoms of O / mole) = 3.011x10²⁴ atoms of O in 5 moles

b. N . Also, 5 moles of nitrogen are:

5 moles N ₓ (6.022x10²³ atoms of N / mole) = 3.011x10²⁴ atoms of N in 5 moles

c. MgCl₂ . Magnesium chloride is a molecule. Again, 1 mole of MgCl₂ contains 6.022x10²³ molecules and 5 moles are:

5 moles MgCl₂ ₓ (6.022x10²³ molecules of MgCl₂ / mole) = 3.011x10²⁴ atoms of MgCl₂ in 5 moles

d. C₂H₃NO. 5 moles of C₂H₃NO are:

5 moles  C₂H₃NO ₓ (6.022x10²³ molecules of  C₂H₃NO / mole) = 3.011x10²⁴ atoms of C₂H₃NO in 5 moles

As you can see, number of molecules of 1 mole doesn't depend on the nature of the substance.

Answer:

A: 2.525 x 10-4 mol

B: 2.583 x 10-4 mol

Explanation:

Part A:

Data Given:

. Temperature of water (H2O) = 21.3°C

Convert Temperature to Kelvin

T = °C + 273

T = 21.3 + 273 = 294.3 K

volume of (H2O) gaseous state = 5.1 mL

Convert mL to liter

1000 mL = 1L

5.1 ml = 5.1/1000 = 0.0051 L

Pressure = 1.2 atm

. no. of moles = ?

Solution

no. of moles can be calculated by using ideal gas formula

PV = nRT

Rearrange the equation for no. of moles

n=PV/RT......... (1)

where

P = pressure

V = Volume

T= Temperature

n = Number of moles

R = ideal gas constant

where

R = 0.08206 L.atm/ mol. K

Now put the value in formula (1) to calculate no. of moles of

n = 1.2 atm x 0.0051 L / 0.08206 L.atm.mol-1. K-1 x 294.3 K

n = 0.0061 atm.L / 24.162 L.atm.mol-1

n = 2.525 x 10-4 mol

no. of moles of gas (H2O) = 2.525 x 10-4 mol

Part B:

Data Given:

Temperature of water (H2) = 21.3°C

Convert Temperature to Kelvin

T = "C + 273

T= 21.3 + 273 = 294.3 K

volume of (H2) gas = 5.2 mL

Convert mL to liter

1000 mL = 1 L

5.2 ml = 5.2/1000 = 0.0052 L

Pressure = 1.2 atm

. no. of moles = ?

Solution

no. of moles can be calculated by using ideal gas formula

PV = nRT

Rearrange the equation for no. of moles

n= PV / RT......... (1)

where

P = pressure

V = Volume

T= Temperature

n = Number of moles

R = ideal gas constant

where

R = 0.08206 L.atm/mol. K

Now put the value in formula (1) to calculate no. of moles of

n = 1.2 atm x 0.0052 L/0.08206 L.atm.mol-1. K-1 x 294.3 K

n = 0.0062 atm.L/ 24.162 L.atm.mol-1

n = 2.583 x 10-4 mol

I

no. of moles of gas (H2) = 2.583 x 10-4 mol

Answer:

Explanation:

1. The element you selected is Sodium. some of the physical properties are

i. Sodium has a strong metallic lustre

ii. Sodium are usually silver white in color

iii. Sodium is soft it can be cut with knife

iv. Sodium are malleable and ductile.

v.  Sodium conduct electricity

Sodium belong to group 1 elements which are called Alkali metals. Sodium have one valency electron and it gives this electron easily during bonding . This is one reason sodium and other alkali metals are very reactive. Sodium can instantly be oxidized by water.  Sodium has a relative atomic mass of approximately 23 amu.

2. There are various models that describe atoms .This models includes John Dalton models, J.J Thompson model, Ernest Rutherford model, Bohr's models etc. This models made us understand the role and location of each sub atomic particles. The models shed more light on subatomic particles like electron which revolve around the nucleus.  It provide more information on what contribute to the weight of an atom.

3. The proton , neutron and electron are subatomic particles of an atom. The proton and the neutron are located at the nucleus of an atom.  The proton and neutron contributes majorly to the weight of an atom. The proton is positively charge while neutron has no charge.

Electron is found to move around the nucleus in cloud. The electron is negatively charge. The electron determines bonding of atoms. An atom is electrically neutral if the number of proton is equal to the number of electron.

4. The four fundamental forces includes weak nuclear forces , strong nuclear forces , gravity and electromagnetic forces.

Weak nuclear forces is responsible for particle decay .Nuclear forces don't play a role in chemical reaction . If they are involve in a reaction it becomes nuclear reaction not chemical reaction.

Strong nuclear forces causes a strong nuclear interaction and it is the strongest among the 4 fundamental forces. This strong force only operate when subatomic particles are much closer to each other.

Gravity force is too weak to affect chemical reaction much. The gravity forces involves the interaction between two objects with energy and mass.

The electromagnetic force act between charged particles like negatively charged electron and positively charged proton. Electromagnetic force is the most important force in chemical bonding as it depends on the arrangement of atoms and the state of their electron. Electromagnetic forces exist in various forms like the covalent bond, metallic, ionic , dipole dipole, hydrogen bonds and many more. The major force involve in chemical bonding is the electromagnetic force.

Answer:

Yes

Explanation:

Yes, A substance can be a lewis acid without being a Bronsted-Lowery acid because there are some substances which cannot donate protons(Bronsted-Lowery acid) but can accept a pair of electron.

For Example:

Let us take the example of BF₃

BF₃ contains no proton so it is not a Bronsted Lowery Acid

However, BF₃ has an incomplete octet with 6 electrons. It needs an electron pair to complete its octet. It accepts a pair of electron to become a Lewis Acid

Answer:

Interesting question, and the answer is yes, a substance can be a Lewis acid but not a Bronsted-Lowrey acid. To see this, let’s take a look at the definitions of each.

Explanation:

Bronsted-Lowrey acid:

A compound that is a hydrogen ion (proton) donor. When dissolved in the solvent in question, these compounds lose a proton to the solution. The concentration of these protons in solution is referred to as acidity, and is measured on the pH scale.

Lewis acid:

A substance that is an electron pair receiver. In solution, free electron pairs will form bonds with the substance, either ionic or covalent. In this definition, a proton is itself an acid, rather than a part of an acid.

A key thing to note here is that, in the Bronsted-Lowrey definition, there must be a proton. That means, all Bronsted-Lowrey acids are of the form  HXn→H++Xn− , showing the dissociation in solution. However, a Lewis acid needs only to have the ability to accept an electron pair, which means that  H+  is a Lewis acid, instead of what makes a compound an acid. Additionally, that means that the number of compounds that qualify as a Lewis acid are expanded. A favorite example of mine is boron trifluoride, or  BF3 . It is a common reagent in organic synthesis, it is a Lewis acid, but does not have any hydrogen, so it cannot be a Bronsted-Lowrey acid

Answer:

Alcohol

Structure: Alcohols are organic molecules assembled from carbon (C), oxygen (O), and hydrogen (H) atoms.

Property: The Boiling Point of Alcohols. Alcohols generally have higher boiling points in comparison to other hydrocarbons having equal molecular masses.

Aldehyde

Structure: DescriptionAn aldehyde is a compound containing a functional group with the structure −CHO, consisting of a carbonyl centre.

Property: The polarity of the carbonyl group notably affects the physical properties of melting point and boiling point, solubility, and dipole moment.

Ketone

Structure: A ketone is a functional group with the structure RC(=O)R', where R and R' can be a variety of carbon-containing substituents.

Property: Ketones are soluble in water but their solubility decreases with increase in the length of the chain.

Fatty Acid

Structure: a fatty acid consists of a straight chain of an even number of carbon atoms, with hydrogen atoms along the length of the chain and at one end of the chain and a carboxyl group (―COOH) at the other end.

Property: Fatty acids are solid at room temperature, while unsaturated fatty acids are liquid.

Ether

Structure: a class of organic compounds characterized by an oxygen atom bonded to two alkyl or aryl groups.

Property: An ether molecule has a net dipole moment due to the polarity of C-O bonds.

The functional group associated with ethanol is -OH, the aldehyde is -COH, the ketone is -CO, the fatty acid is -COOH, and ether is ROR.

The functional groups have been the atoms that have different constituents and properties with respect to other groups.

The functional group associated with the following groups has been:

The functional group associated with ethanol is -OH, the aldehyde is -COH, the ketone is -CO, the fatty acid is -COOH, and ether is ROR.

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Answer:

Volume=mass in g /density

Answer: 40cm^3 or 40ml

Explanation:

[tex]Density=\frac{mass}{volume}[/tex]

so 5=200/V

V=200/5

V=40cm^3

Answer:

0.756 J

Explanation:

Temperature change (delta T) = 0.855 degrees Celsius

Mass of water (m) = 0.2067 g

Specific heat capacity of water (c) = 4.28 J/g degrees C

Heat added = m * c * delta T

= (0.2067 * 4.28 * 0.855) J

= 0.756 J

Answer:

a

Explanation:

Answer:

basic solution.

Explanation:

has a pH of 12.

it turns clear indicator pink.

it contains hydroxide ions which conduct electricity

Answer:

F

Explanation:

"The mass of the products is equal to the mass of the reactants" is true about the principle of the conservation of mass.

So, option f is correct one.

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Answer:

C) Liquids and gases

Explanation:

The correct answer would be liquids and gases.

The molecules of liquids and gases move randomly when held in a container. The random movement causes a collision between the molecules of the liquids/gases and between the walls of the container, creating pressure in the process. This is unlike the molecules of solids that vibrate about fixed positions.

Hence, the correct option is C.

Answer: 1.29 moles of ethylene glycol must be added to 1 kg of water to make a solution with a freezing point of -2.4°C. Molality of solution is 1.29 m.

Explanation:

Depression in freezing point is given by:

[tex]\Delta T_f=i\times K_f\times m[/tex]

[tex]\Delta T_f=T_f^0-T_f=(0-(-2.4))^0C=2.4^0C[/tex] = Depression in freezing point

i= vant hoff factor (for non electrolyte , i = 1)

[tex]K_f[/tex] = freezing point constant for water= [tex]1.86^0C/kgmol[/tex]

m= molality =[tex]\frac{\text{moles of solute}}{\text{weight of solvent in kg}}[/tex]

m= molality =[tex]\frac{x}{1kg}[/tex]

[tex]2.4^0C=1\times 1.86^0C/kgmol\times \frac{x}{1kg}[/tex]

[tex]x=1.29[/tex]

Molality = [tex]\frac{\text{moles of solute}}{\text {weight of solvent in kg}}=\frac{1.29mol}{1kg}=1.29m[/tex]

Thus 1.29 moles of ethylene glycol must be added to 1 kg of water to make a solution with a freezing point of -2.4°C. Molality of solution is 1.29 m.

Answer:

1) C (m=T f/Kf)

2) 2.4 C

3) 1.3 m

4) 1.3 moles

Explanation:

This is correct on ed

Answer:

The answer is 3.87 J/g°C

Explanation:

Here is the equation we are going to use:

[tex]C=\frac{q}{mT}[/tex]

C= specfic heat in J/g°C

q = heat in joules (J)

m = mass in grams (g)

T = change in temperature

Here is what is given:

q = 849 J

m = 95.4 g

T = 48.0 - 25.0 = 23°C

Find:

Specific heat capacity in J/g

The first thing we are going to do is plug everything into the equation:

[tex]C = \frac{849J}{(9.54g)(23degreesC)}[/tex]

Then we are going to solve for C

[tex]C = \frac{849J}{219.42gC} = 3.87 J/gCelsius[/tex]

Hope this helps!

Answer:

The answer is 3.87 J/gC

Answer:

C. The electron clouds are negatively charged and repel each other as far apart as possible

Explanation:

This is the basis of VSEPR theory.

The angles between the electron clouds determine the shapes of the molecules.

B. and D. are wrong. All electron pairs are negatively charged.

The electrons affect the structure of a molecule because the bonding pairs are positively charged and lone pairs are negatively charged and they push each other into certain shapes.

Every atom or molecule consist some kind of geometry or shapes like linier, tetrahedral, square planner, octahedral etc. with some bond length and angles present with them.

The bond pairs in a geometry is made up with positive charge and lone pairs present on the atom in the form of negative charge as they both are opposite in nature and repel or push each other in opposite direction.

Due to this phenomena the structure of the atom gets effected and geometry will change on the basis of lone pair and bond pair repulsion.

Therefore, electrons affect the structure of a molecule because the bonding pairs are positively charged and lone pairs are negatively charged and they push each other into certain shapes.

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Answer:

The correct option is;

d. Explicit knowledge

Explanation:

Explicit knowledge is the knowledge that can be easily articulated documented stored in a retrieval system accesses, transmitted and shared with others

Tacit knowledge is the skill developed by an individual based on actual experience such that such knowledge comprise of both facts and perspectives

Hence explicit knowledge and tacit knowledge are complementary

The operations performed by Kaia include documentation, storing in a retrieval system (her project report) and accessing what she documented, this is an example of explicit knowledge.

Answer:

In order to determine the number of moles of the given volume of Ar, divide the given volume by the molar volume of an ideal gas,  

22.710 L/mol

Explanation:

So you have a volume of  6 .5

6.5L / 22.710 L/mol

L is eliminate .

6.5/ 22.710 L/mol = 0.286 mol

Using the older STP values of  0 ∘ C  or  273.15 K , and pressure of  1 atm , molar volume is  22.414 L/mol .

6.5L /22.414 L/mol .= 0.289 mol

Answer:

A. C(s) + O2(g) → CO2(g) + 393.5 kJ

Explanation:

The formation of carbon IV oxide (CO2) is an exothermic process. n exothermic process is a chemical process in which heat is evolved. Speaking in lay man's terminology, heat is one of the 'products' of the reaction. This implies that heat is evolved by the process.

The formation of CO2 is always a combustion reaction where heat is evolved or released by the reaction system. Hence the reaction could be shown as;

C(s) + O2(g) → CO2(g) + 393.5 kJ

This implies that 393.5 kJ of energy is released in the reaction in the form of heat. Hence the answer given in the answer box.

Answer: C(s) + O2(g) → CO2(g) + 393.5 kJ

Answer:

It is decreasing the temperature of the reactant mixture.

Explanation:

Just took the test

In order to decrease the number of collisions and energy of reactant molecules, the temperature of the reactant mixture would need to be decreased as well.

The temperature of reactants is proportional to the average kinetic energy of the molecules of the reactants.

Also, the higher the average kinetic energy of the reactant molecules, the higher their chances of colliding and reacting to form products.

Thus, in order to decrease their energy and collision frequency, the temperature of the reactant mixture needs to be decreased.

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Answer:

1. 0.56 mole of electron.

2. 0.28 mole of Co .

3. 16.52g of Co.

Explanation:

The following data were obtained from the question:

Current (I) = 15A

Time (t) = 1 hr = 1 x 60 x 60 = 3600secs

Next, we shall determine the quantity of electricity, Q flowing in electrolyte. This is illustrated below:

Quantity of electricity (Q) = current (I) x Time

Q = It

Q = 15 x 3600

Q = 54000C.

1. Determination of the moles of electrons used to electrolyzed the solution. This is illustrated below:

96500C = 1 mole of electron

Therefore, 54000C = 54000/96500 = 0.56 mole of electron.

Therefore, 0.56 mole of electron was used to electrolyze the solution.

2. Determination of the number of mole of Co produced at the cathode. This is illustrated below:

At the cathode:

Co2+ + 2e —> Co

From the balanced equation above,

2 moles of electron produce 1 mole of Co.

Therefore, 0.56 mole of electron will produce = 0.56/2 = 0.28 mole of Co.

Therefore, 0.28 mole of Co is produced at the cathode.

3. Determination of the mass of Co produced at the cathode. This can be achieved by doing the following:

Molar mass of Co = 59g/mol

Number of mole of Co = 0.28 mole

Mass of Co =..?

Mass = mole x molar mass

Mass of Co = 0.28 x 59

Mass of Co = 16.52g

Therefore, 16.52g of Co is produced at the cathode.

Answer:

A cation that has a smaller radius than the atom.

Explanation: when electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom.

When electrons are removed from the outermost shell of a calcium atom, the atom becomes  a cation that has a smaller radius than the atom. Therefore, the correct option is option D.

Atom, the smallest unit of matter that may be separated without releasing electrically charged particles. It is also the smallest unit of matter with the characteristics of a chemical element. As a result, the atom is indeed the fundamental building component of chemistry.

The majority of the atom comprises empty space. The rest of the structure is made up of a positive-charged nucleus of neutrons and protons surrounding by a cloud of electrons with negative charges. In comparison to electrons, the lightest energized particles in nature, the nuclei is small and dense. When electrons are removed from the outermost shell of a calcium atom, the atom becomes  a cation that has a smaller radius than the atom.

Therefore, the correct option is option D.

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Answer:

Explanation:

A battery

Answer:

Ac motor is in this images