An object has a mass of 72 kg. What is its weight?

The question is incomplete, the complete question is;

A student prepared several aqueous sodium chloride (NaCl) solutions to observe boiling point elevation at various molal concentrations, however, several errors were made throughout the procedure. Determine whether these errors would cause the observed boiling point to be increased or decreased relative to the expected boiling point, based on the procedure, or have no effect on the experimental results.

* The flask is washed with water but not thoroughly dried before preparing the solution

* The mass of NaCl used to prepare the solution is 5.400 grams instead of 4.400 grams

* Some of the prepared solution splashes out of the flask prior to observation of the boiling point

* When making the salt solution, 55.0 milliliters of water is added instead of 50.0 milliliters

Answer:

The flask is washed with water but not thoroughly dried before preparing the solution  - decrease

The mass of NaCl used to prepare the solution is 5.400 grams instead of 4.400 grams

-increase

Some of the prepared solution splashes out of the flask prior to observation of the boiling point- have no effect

When making the salt solution, 55.0 milliliters of water is added instead of 50.0 milliliters- decrease

Explanation:

If the flask is washed but not dried, then the solution will be further diluted than expected. As a result of this further dilution, the observed boiling point will be less than the expected boiling point because the boiling point depends on the solution's concentration.

If more solute is added than expected, the concentration of the solution is increased and the boiling point also increases above the expected boiling point due to the increase in amount of solute present.

If some of the solution splashes out of the flask prior to boiling, the boiling point is not affected because the concentration of the solution was not altered. The boiling point only changes when the concentration of the solution is changed.

If 55 ml of water is added instead of 50 ml, the solution is now more dilute than expected thereby reducing the concentration of the solution and the boiling point. Remember that, as the concentration of the solution decreases, the boiling point decreases accordingly.

Answer: a)  [tex]Fe[/tex] is the limiting reagent

b) 3.59 g

c) 11.6g

Explanation:

[tex]4Al_2O_3+9Fe\rightarrow 3Fe_3O_4+8Al[/tex]  

To calculate the moles :

[tex]\text{Moles of} Al_2O_3=\frac{27.5g}{102g/mol}=0.27moles[/tex]

[tex]\text{Moles of} Fe=\frac{8.4g}{56g/mol}=0.15moles[/tex]

According to stoichiometry :

a) 9 moles of [tex]Fe[/tex]  require= 4 moles of [tex]Al_2O_3[/tex]

Thus 0.15 moles of [tex]Fe[/tex] will require=[tex]\frac{4}{9}\times 0.15=0.067moles[/tex]  of [tex]Al[/tex]

Thus [tex]Fe[/tex] is the limiting reagent as it limits the formation of product and [tex]Al[/tex] is the excess reagent.

b) As 9 moles of [tex]Fe[/tex] give = 8 moles of [tex]Al[/tex]

Thus 0.15 moles of [tex]Fe[/tex] give =[tex]\frac{8}{9}\times 0.15=0.133moles[/tex]  of [tex]Al[/tex]

Mass of [tex]Al=moles\times {\text {Molar mass}}=0.133moles\times 27g/mol=3.59g[/tex]

c) As 9 moles of [tex]Fe[/tex] give = 3 moles of [tex]Fe_3O_4[/tex]

Thus 0.15 moles of [tex]Fe[/tex] give =[tex]\frac{3}{9}\times 0.15=0.05moles[/tex]  of [tex]Fe_3O_4[/tex]

Mass of [tex]Fe_3O_4=moles\times {\text {Molar mass}}=0..05moles\times 231.5g/mol=11.6g[/tex]

Answer:

Mass =  76986  g

Explanation:

Given data:

Dimensions of tank = 126 cm× 47 cm× 13 cm

Mass of water required to filled = ?

Solution:

First of all we will calculate the volume of tank which is equal to the volume of water required to fill it.

Volume = length ×height ×width

Volume = 126 cm × 13 cm× 47 cm

Volume = 76986 cm³

Mass of water:

Mass = density × volume

density of water is 1 g/cm³

Mass = 1 g/cm³× 76986 cm³

Mass =  76986  g

Answer:

1.51×10²³ atoms.

Explanation:

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

Mass of Calcium (Ca = 10 g

Number of atom of Calcium (Ca) =?

The number of atoms present in 10 g of Ca be obtained as follow:

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ atoms. This implies that 1 mole Ca contains 6.02×10²³ atoms.

1 mole of Ca = 40 g.

Now, if 40 g of Ca contains 6.02×10²³ atoms.

Therefore, 10 g of Ca will contain = (10 × 6.02×10²³) / 40 = 1.51×10²³ atoms.

Thus, 10 g of calcium contains 1.51×10²³ atoms.

Answer:

A) 2

Explanation:

Answer:

2, i got it right thanks to the other user :) <3

Explanation:

Answer:

the change in energy when one substance dissolves in another

Explanation:

The enthalpy changes are the heat changes accompanying physical and chemical changes. Actually, an enthalpy change is the difference between the sum of the heat contents of products (final state) and sum of the heat contents of reactants (initial state).

There are basically two types of heat changes that accompanies are reaction which are:

Therefore, the change in energy when one substance dissolves in another defines the enthalpy of solution.

Enthalpy of solution is the heat liberated or absorbed when one mole of a substance (solute) is dissolved in a specified volume of solvent (water).

Answer:

0.05M is the concentration of the phosphate buffer

Explanation:

A buffer is defined as the aqueous mixture of a weak acid (KH₂PO₄) and its conjugate base (K₂HPO₄). The concentration of this buffer is the sum of the concentrations of the weak acid and the conjugate base, that is:

Concentration of phosphate buffer = 0.02M + 0.03M

=

Answer:

Because sugar has no ions in the solution

Explanation:

Pure water contains very few ions, so it does not conduct electricity very well. When table salt is dissolved in water, the solution conducts very well, because the solution contains ions. When sugar is dissolved in water, the solution does not conduct electricity, because there are no ions in the solution.

In basic words the more ions in the solution there is a better chance to conduct electricity.

Answer:

Fluorine (F)

Explanation:

The poorest conductor of electricity from the given choices is fluorine. This is because fluorine is a non - metal.

Like other non - metals, fluorine does not conduct electricity.

Only metals are known to conduct electricity and heat readily.

Semi - metals like silicon will conduct electricity under specific condition.

The free mobile electrons in metals makes it easy for them propagate electricity

Answer:

Molecules along the surface of a liquid behave differently than those in the bulk liquid.

Cohesive forces attract the molecules of the liquid to one another.

Water forming a droplet as it falls from a faucet is a primary example of surface tension.

Explanation:

Surface tension is the force that stretches the liquid surface. This force acts normal to the surface. It is the downward force that acts on the surface of the liquids which is due to the cohesive forces of the liquids.

The water molecules are bonded by a strong hydrogen bond force which is between hydrogen atom and the electronegative oxygen atom. At the surface the water molecules are attracted strongly by other water molecules which lies below the surface and are stretched at the surface. Thus the water molecules at the surface acts differently than in the bulk liquid.

Mercury have a strong cohesive force than the water and have a higher surface tension force than the water.

Surface water acquires minimum surface area, hence acquiring spherical shape of water.

Explanation:

Türküm ben yanlisikla siteye girdim.

Answer:

breaks

Explanation:

I think its braks

Answer:

Explanation:

a )

Average reaction rate between 0 and 1500s

Time duration = 1500 s

moles reacted = .184 - .016 = .168 moles

Moles reacted per second = .168 / 1500

= 112 x 10⁻⁶ moles /s

b )

Average reaction rate between 200 and 1200s

Time duration = 1000 s

moles reacted = .129 - .019 = .11 moles

Moles reacted per second = .11 / 1000

= 110 x 10⁻⁶ moles /s

c )

the instantaneous rate of the reaction at t=800s

We shall assume that between 500 s and 1200 s , rate of reaction is uniform

rate between 500 and 1200

Time duration = 700 s

moles consumed = .069 - .019 = .05 moles

Rate of reaction = .05 / 700

= 71 .4 x 10⁻⁶ moles / s

This will also be instantaneous rate of reaction at t = 800 s .

Answer:

Wave

Explanation:

Wave refers to any disturbance that carries energy from one place to another.

Wave refers to disturbance or variation that occur in a body travelling or in motion which travels from one medium to another by transmitting energy from one location which is the origin to another location without transporting matter.

Therefore, Wave refers to any disturbance that carries energy from one place to another

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Answer:

Salivation allows the ingestion of food while digestive juices aids breakdown of food and absorption of nutrients.

Explanation:

When food is taken into the mouth, the presence of food triggers a nervous reflex that causes the salivary gland to produce saliva in the mouth. Once the food particles have been ingested the digestive system breaks down the food into smaller components with the aid of the digestive juices.

Answer:

e. I, At

Explanation:

Hello!

In this case, since the periodic trends of a series of elements belonging to the same group towards physical and chemical properties tend to be the same when closer in period, we notice that Mg and Al, Br and Kr and As and Br are close but in period, not in the same group; therefore e. I, At, iodine and astatine, are going to tend to exhibit the greatest similarity in their physical  and chemical properties.

Best regards!

Answer:

C. Plate tectonic collisions can create mountains.

Answer:

They can make them larger

Explanation:

They go up under a mountain and then the mountains rise up

Answer:

It replaces Br in MgBr2.

Explanation:

Hello!

In this case, when carrying out double displacement reactions, we need to take into account that cations and anions are switched; thus, when LiCl and MgBr2 react, since Li and Mg are the cations, Br and Cl switch as shown below:

[tex]2LiCl+MgBr_2\rightarrow 2LiBr+MgCl_2[/tex]

Thus, chlorine replace Br in MgBr2 to form MgCl2.

Best regards!

Answer:

6moles of Mg

Explanation:

The reaction expression is given as:

          BO₃   +    3Mg   →    3MgO    +    B

Given:

Number of moles of B produced  = 2 moles

Unknown:

Number of moles of Mg required  = ?

Solution:

  From the balanced reaction expression:

          1 mole of B is produced from 3 moles of Mg

          2 moles of B will be produced from 2 x 3  = 6moles of Mg

Answer:

B. Similar fossils were found in different continents.

Answer:

B. Similar fossils were found in different continents.

Explanation:

Answer: inside

Explanation:

Answer:

direct and indirect contact

Explanation:

if you touch a doorknob right after an infected person than you make be exposed to the disease.

Mass of sample : 1987.5 g≈1990 g

Given

12% mass of Lithium chlorate

Required

Mass of sample

Solution

%mass = (mass of solute/mass of solution) x 100%

mass of solute = mass of Lithium chlorate = 238.5 g

Input the value :

12/100(0.12) = 238.5 g : mass of solution

mass of solution =238.5 : 0.12

mass of solution = 1987.5≈1990 g

Answer: Percent recovery is 47.34 %

Explanation:

Percent yield is defined as the ratio of experimental yiled to theoretical yield in terms of percentage.

[tex]{\text{ percent yield}}=\frac{\text{amount recovered}}{\text{total amount}}\times 100[/tex]

Putting in the values we get:

[tex]{\text{ percent yield}}=\frac{0.732}{1.546}\times 100=47.34\%[/tex]

Therefore, the percent recovery is 47.34 %

Answer: The equipment best suited for extinguishing each type of fire are listed below:

--> Fire extinguisher: Large fire on the floor

--> Overturned beaker: Small benchtop fire

--> Fire blanket: clothing fire.

Explanation:

Fire outbreaks is a common event that can be prevented in a standard chemistry laboratory with the aid of fire safety equipments.

The method used by these equipments to extinguish fire is to suffocate the fire by obstructing the source of oxygen, by reducing the heat with the use of water and removing the fuel or oxygen source.

These fire safety equipments should be highly visible and easily accessible in a laboratory. Example of fire safety equipments includes:

--> Fire extinguisher: A laboratory personnel needs to be trained in the use of this since it's made up of different types. it can be used to extinguish ( put out) large fire on the floor.

--> Overturned beaker: this can be used to suffocate small fire on the bench which is also common in the laboratory.

-->Fire blanket: This should be used in the event that a person’s body or clothing catches fire.

Answer: not 100% but maybe Visable Light...sorry if thats wrong

Explanation:

Thermal energy is the another name for infrared energy.

Infrared radiation is a type of radiant energy that is  not visible to human eyes but we can feel as heat energy.

Infrared radiation (IR), also known as thermal radiation. It is that band of energy in the electromagnetic radiation spectrum with wavelengths between 780 nm and 1 mm so we can conclude that thermal energy is the another name for infrared energy.

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Answer:

See explanation

Explanation:

Weathering refers to the breakdown of rocks to form soil. There are several agents of weathering.

In warmer regions, there are more vegetation and microorganisms and they increase the rate of biological weathering.

Since weathering leads to the formation of soil and the rate of weathering is greater in warmer climates, it also follows that as temperature increases and more soil is formed, erosion will happen faster at this higher temperature owing to the presence of more soil compared to colder climates.

There is a huge and direct effect of temperature on the rates of erosion.

The highest rate of weathering occurs in warm and wet climate because in warm and wet climatic regions, more rainfall occurs which increase the rate of weathering. Rainfall and temperature can affect the rate in which rock weathering occurs.

High temperatures and greater rainfall increase the rate of chemical weathering. Rocks in tropical regions exposed to abundant rainfall so we can conclude that hot temperatures weather much faster than similar rocks residing in cold, dry regions.

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Answer:

i = 2.79

Explanation:

The excersise talks about the colligative property, freezing point depression.

Formula to calculate the freezing point of a solution is:

Freezing point of pure solvent - Freezing point of solution = m . Kf . i

Let's replace data given. (i = Van't Hoff factor, numbers of ions dissolved in solution)

48.1°C - 44°C = 0.15 m . 9.78°C/m . i

4.1°C / (0.15 m . 9.78°C/m) = i

i = 2.79

In this case, numbers of ions dissolved can decrease the freezing point of a solution, which is always lower than pure solvent.

Answer:

8

Explanation:

Answer:

See explanation below

Explanation:

First, let's write the reaction:

NH₄SH(s)   <------> H₂S(g) + NH₃(g)

The reaction is already balanced so we don't need to do anything else.

Second, let's take into account the following. The Kc expression for this reaction, only compounds in gaseous state are the only ones that contribute to the equilibrium. Solid and liquid do not contribute to the Kc expression. This is because solid and liquid have a constant concentration near to 1, so, it won't do any difference.

Knowing this, the Kc expression for this reaction is:

Kc = [H₂S] [NH₃]

Now, to calculate Kp from Kc, there's an expression that helps a lot to do this. The expression is the following:

Kp = Kc (RT)ᵃⁿ    (1)

Where:

R: universal constant of gases

T: Temperature in K

ᵃⁿ = difference of the coefficients of the reaction.

This expression comes from the fact that Kp is an expression that instead of working with concentrations, it works with pressure.

If we use the ideal gas equation we have:

PV = nRT

Solving for P:

P = nRT/V        and C = n/V   so

P = CRT

If we now replace this, in the Kp expression of equilibrium we have:

Kp = pH₂S * pNH₃

Kp = ([H₂S]RT)¹ ([NH₃]RT)¹

Kp = (RT)¹⁺¹ ([H₂S] [NH₃])

Kp = (RT)²Kc

So finally the expression for Kp would be:

Hope this helps