Students were provided with a sample of a pure element to examine. They made a list of its observable properties: solid at room temperature, shiny, malleable, and a good conductor of heat. Based on these properties, which element were the students most likely observing? *

Sulfur
Tin
Silicon
Carbon

Answer:

(decreasing particle size) C

Explanation: That is one of the answers, if there are more I am sorry.

Answer:

A. The Swallowing reflex

Explanation:

Dysphagia Is a a condition that makes swallowing difficult.

Answer:

.176 M

Explanation:

set the number of moles of the base equal to the number of moles of acid.

(1.008 mol/L)(26.23 x 10^-3 L)=(150.2x10^-3 L)(x)

x = .176030892 mol/L

Answer:

density

Explanation:

Density is an important measurement. It has an unit: g/mL or kg/L, ...

Evaporation, freezing, melting are the processes in which the substances change their states. Other processes are: condensation, sublimation, deposition.

...

Hope this answer can help you. Have a nice day!

Answer:

[tex]m_{PbI_2}=18.2gPbI_2[/tex]

Explanation:

Hello,

In this case, we write the reaction again:

[tex]Pb(NO_3)_2(aq) + 2 KI(aq)\rightarrow PbI_2(s) + 2 KNO_3(aq)[/tex]

In such a way, the first thing we do is to compute the reacting moles of lead (II) nitrate and potassium iodide, by using the concentration, volumes, densities and molar masses, 331.2 g/mol and 166.0 g/mol respectively:

[tex]n_{Pb(NO_3)_2}=\frac{0.14gPb(NO_3)_2}{1g\ sln}*\frac{1molPb(NO_3)_2}{331.2gPb(NO_3)_2} *\frac{1.134g\ sln}{1mL\ sln} *96.7mL\ sln\\\\n_{Pb(NO_3)_2}=0.04635molPb(NO_3)_2\\\\n_{KI}=\frac{0.12gKI}{1g\ sln}*\frac{1molKI}{166.0gKI} *\frac{1.093g\ sln}{1mL\ sln} *99.8mL\ sln\\\\n_{KI}=0.07885molKI[/tex]

Next, as lead (II) nitrate and potassium iodide are in a 1:2 molar ratio, 0.04635 mol of lead (II) nitrate will completely react with the following moles of potassium nitrate:

[tex]0.04635molPb(NO_3)_2*\frac{2molKI}{1molPb(NO_3)_2} =0.0927molKI[/tex]

But we only have 0.07885 moles, for that reason KI is the limiting reactant, so we compute the yielded grams of lead (II) iodide, whose molar mass is 461.01 g/mol, by using their 2:1 molar ratio:

[tex]m_{PbI_2}=0.07885molKI*\frac{1molPbI_2}{2molKI} *\frac{461.01gPbI_2}{1molPbI_2} \\\\m_{PbI_2}=18.2gPbI_2[/tex]

Best regards.

Answer:

Mass PbI2 = 18.19 grams

Explanation:

Step 1: Data given

Volume solution = 99.8 mL = 0.0998 L

mass % KI = 12.0 %

Density = 1.093 g/mL

Volume of the other solution = 96.7 mL = 0.967 L

mass % of Pb(NO3)2 = 14.0 %

Density = 1.134 g/mL

Step 2: The balanced equation

Pb(NO3)2(aq) + 2 KI(aq) ⇆ PbI2(s) + 2 KNO3(aq)

Step 3: Calculate mass

Mass = density * volume

Mass KI solution = 1.093 g/mL * 99.8 mL

Mass KI solution = 109.08 grams

Mass KI solution = 109.08 grams *0.12 = 13.09 grams

Mass of Pb(NO3)2 solution = 1.134 g/mL * 96.7 mL

Mass of Pb(NO3)2 solution = 109.66 grams

Mass of Pb(NO3)2 solution = 109.66 grams * 0.14 = 15.35 grams

Step 4: Calculate moles

Moles = mass / molar mass

Moles KI = 13.09 grams / 166.0 g/mol

Moles KI = 0.0789 moles

Moles Pb(NO3)2 = 15.35 grams / 331.2 g/mol

Moles Pb(NO3)2 = 0.0463 moles

Step 5: Calculate the limiting reactant

For 1 mol Pb(NO3)2 we need 2 moles KI to produce 1 mol PbI2 and 2 moles KNO3

Ki is the limiting reactant. It will completely be consumed ( 0.0789 moles). Pb(NO3)2 is in excess. There will react 0.0789/2 = 0.03945 moles. There will remain 0.0463 - 0.03945 = 0.00685 moles

Step 6: Calculate moles PbI2

For 1 mol Pb(NO3)2 we need 2 moles KI to produce 1 mol PbI2 and 2 moles KNO3

For 0.0789 moles KI we'll have 0.0789/2 = 0.03945 moles PbI2

Step 7: Calculate mass of PbI2

Mass PbI2 = moles PbI2 * molar mass PbI2

Mass PbI2 = 0.03945 moles * 461.01 g/mol

Mass PbI2 = 18.19 grams

Answer:

see explanations

Explanation:

              PCl₅  =>     PCl₃     +     Cl₂

C(eq):   [PCl₅]       0.054M        0.34M

a.  Keq = [PCl₃][Cl₂]/[PCl₅]

b.  7.9 = (0.054)(0.34)/[PCl₅] => [PCl₅] = (0.054)(0.34)/(7.9) = 0.0023M

c.  If [PCl₃] = 0.054M; [Cl₂] = 0.34M and [PCl₅] = 0.0023M then the reaction is at equilibrium and will not shift forward or in reverse. In order to determine if reaction is not at equilibrium, a set of concentration values needs to be given in problem, used to calculate Qeq and compared to the given Keq value.  The following defines direction of shift ...

Keq  <  Qeq  =>  rxn shifts left

Keq  =  Qeq  =>  rxn is at equilibrium (no shift)

Keq  >  Qeq  =>  rxn shifts right

NOTE: If Keq is listed first followed by Qeq in the above conditions, the inequality symbol indicates direction of shift.

Answer:

Option C

Explanation:

A double displacement reaction is the one in which two chemical compounds having a cation and anion in each exchange their positive and negative ions thereby forming new compounds or products.

Here,

The first compound [tex]PbCl_2[/tex] has a positive ion [tex]Pb[/tex] and negative ion [tex]Cl^-[/tex]

Like wise the second compound [tex]Ag(NO_3)[/tex] has a positive ion [tex]Ag[/tex] and negative ion [tex]NO_3[/tex]

The new compounds will be formed when cation of one compound attaches with the anion of other compound. Hence the new compounds are

[tex]Pb(NO_3)_2[/tex]

[tex]AgCl[/tex]

This is example of double displacement reaction.

Option C is correct

Answer:

120.4 gradius Celcius

Explanation:

Please see the step-by-step solution in the picture attached below.

Hope this answer can help you. Have a nice day!

Answer:

[tex]n=0.0747mol[/tex]

Explanation:

Hello,

In this case, since we can consider hydrogen gas as an ideal gas, we check the volume-pressure-temperature-mole relationship by using the ideal gas equation:

[tex]PV=nRT[/tex]

Whereas we are asked to compute the moles given the temperature in Kelvins, thr pressure in atm and volume in L as shown below:

[tex]n=\frac{105kPa*\frac{0.009869atm}{1kPa}*1.75L}{0.082\frac{atm*L}{mol*K}*(23+273.15)K} \\\\n=0.0747mol[/tex]

Best regards.

Answer:

Metamorphic rocks are formed from pre-existing rock and sediment materials. They are formed when igneous, sedimentary, or other pre-existing metamorphic rocks are exposed to the heat and pressure as well as super-heated mineral-rich fluids. They are compacted together to form a new rock altogether. Metamorphism does not include the melting or liquefaction of the pre-existing rock. Instead, it compacts them and crushes them, pushing them together at extreme heat and pressure to form a new rock altogether composed of sedimentary, igneous, and other metamorphic rock. It's the rock hybrid of the geologic world.

Metamorphism is similar to when you squish playdough together, it doesn't form a new playdough color (unless you REALLY mixed that poor playdough together). It forms an amalgamation of different colors and patterns made from the other rock.

Taken from a paper I once wrote I explained this again:

"Metamorphic rocks are formed when pre-existing rocks and their minerals are compressed and altered by Earth’s internal processes; interior pressure, temperature (heat), and chemical reactions. The minerals and pre-existing rock necessary for the creation of metamorphic rock must then also be located deep underground if such processes are expected to make an impact and create a metamorphic rock."

Answer:

[tex]\Delta V = 234.736\,mL[/tex]

Explanation:

The quantity of moles of ethanol in the solution is:

[tex]n_{C_{2}H_{5}OH} = \left(\frac{597\,mL}{1000\,mL} \right)\cdot \left(8.35\,\frac{mol}{L} \right)[/tex]

[tex]n_{C_{2}H_{5}OH} = 4.985\,mol[/tex]

The mass and volume of ethanol in the solution are, respectively:

[tex]m_{C_{2}H_{5}OH} = (4.985\,mol)\cdot \left(46.07\,\frac{g}{mol} \right)[/tex]

[tex]m_{C_{2}H_{5}OH} = 229.658\,g[/tex]

[tex]V_{C_{2}H_{5}OH} = \frac{229.658\,g}{0.7893\,\frac{g}{mL} }[/tex]

[tex]V_{C_{2}H_{5}OH} = 290.964\,mL[/tex]

The difference between the total volume of water and ethanol mixed to prepare the solution and the actual volume of solution is:

[tex]\Delta V = (525\,mL+597\,mL) - (597\,mL + 290.964\,mL)[/tex]

[tex]\Delta V = 234.736\,mL[/tex]

The difference in volume between the total volume of water and ethanol is ΔV =234.736 mL.

The quantity of moles of ethanol in the solution is:

[tex]nC_2H_5OH=\frac{597mL}{1000mL} *8.35mol/L\\\\nC_2H_5OH=4.985 moles[/tex]

The mass and volume of ethanol in the solution are, respectively:

[tex]mC_2H_5OH=4.985moles*46.07g/mol\\\\mC_2H_5OH=229.685g[/tex]

[tex]VC_2H_5OH=\frac{229.685g}{0.7893g/mL} \\\\VC_2H_5OH=290.964mL[/tex]

The difference between the total volume of water and ethanol mixed to prepare the solution and the actual volume of solution is:

ΔV= (525mL+597mL)- (597mL + 290.964 mL)

ΔV= 234.736mL

Find more information about Moles here:

brainly.com/question/13314627

Answer:

I believe it is C.Shelter.

Answer:

C

Explanation:

The butterflies use the trees for shelter, because the trees protect them from the weather and the cold air.

Answer:

Unfavorable reactions: Reaction A and Reaction B.

Coupled reactions favorable: Reactions B and C and Reactions A and C.

Net change:

Reactions B and C : -14.2kJ/mol

Reactions A and B : 30.1kJ/mol

Reactions A and C: -16.7kJ/mol

Explanation:

A reaction is thermodynamically favorable (spontaneous) if ΔG < 0. Thus, the unfavorable reactions -ΔG > 0- are:

Reaction A and reaction B.

When reaction C is coupled with reaction B and reaction A the chemical equation is:

ATP + fructose-1,6-phosphate ⟶ ADP + fructose-1,6-bisphosphate

ΔG = 16.3 - 30.5 = -14.2 kJ/mol

ATP + glucose ⟶ ADP + glucose-6-phosphate

ΔG = 13.8 - 30.5 = -16.7 kJ/mol

The coupled reaction of A and B has a change in free energy of:

ΔG = 13.8 + 16.3 = 30.1 kJ/mol

Answer:

the claim is that when people avoid storms they hide in any secret place in there house

Explanation:

when people do that they don't even have to worry about a single thing that will happen to them

Answer:

D) SrCO3(s) + 2 HNO2(aq) → Sr(NO2)2 + H2O + CO2(g)

Explanation:

When an acid react with carbonate, it produces nitrate, carbon-dioxide gas and water molecule. When nitrous acid react with Strontium carbonate, three products are formed i. e. Strontium nitrate, carbon-dioxide gas and water. In the reaction, both nitrous acid and Strontium carbonate exchange their partners with each other and forming a different products.

Answer:

Option E is correct.

The net ionic equation is given as

SrCO₃(s) + 2H⁺ → Sr²⁺ + H₂O + CO₂(g)

Explanation:

When acids react with carbonate compounds, it leads to the liberation of CO₂, hence, when an aqueous solution of HNO₂ is poured onto a solid pile of SrCO₃, the balanced overall equation is given as

SrCO₃(s) + 2HNO₂(aq) → Sr(NO₂)₂ + H₂O + CO₂(g)

But for the net ionic reaction, it is obtained by eliminating ions that occur on both sides of the overall reaction. Note that ions exist onlubone the aqueous compounds.

Hence, the two aqueous compounds that exist in the balanced overall equation are

2HNO₂(aq) on the left hand side and Sr(NO₂)₂ on the right hand side

In their ionic form, 2HNO₂ ⇌ 2H⁺ + 2NO₂⁻

And Sr(NO₂)₂ ⇌ Sr²⁺ + 2NO₂⁻

And it is evident that the ion that occurs on both sides and needs to be deleted is NO₂⁻,

Hence, the net ionic equation is

SrCO₃(s) + 2H⁺ → Sr²⁺ + H₂O + CO₂(g)

Hope this Helps!!!

Answer:The answer to this question comes from experiments done by the scientist Robert Boyle in an effort to improve air pumps. In the 1600's, Boyle measured the volumes of gases at different pressures. Boyle found that when the pressure of gas at a constant temperature is increased, the volume of the gas decreases. when the pressure of gas is decreased, the volume increases. this relationship between pressure and volume is called Boyle's law.

Explanation: So, at constant temperature, the answer to your answer is: the volume decreases in the same ratio as the ratio of pressure increases.

BUT, in general, there is not a single answer to your question. It depend by the context.

For example, if you put the gas in a rigid steel tank (volume is constant), you can heat the gas, so provoking a pressure increase. But you won't get any change in volume.

Or, if you heat the gas in a partially elastic vessel (as a tire or a soccer ball) you will get both an increase of volume AND an increase of pressure.

FINALLY if you inflate a bubblegum ball, the volume will be increased without any change in pressure and temperature, because you have increased the NUMBER of molecules in the balloon.

There are many other ways to change volume and pressure of a gas that are different from the Boyle experiment.

Answer:

[tex]\frac{1}{24}[/tex]

Explanation:

Given:

For a school event, 1/6 of the athletic field is reserved for the fifth -grade classes and the reserved part of the field is divided equally among the 4 fifth grade classes in the school.

To find: fraction of the whole athletic field reserved for each fifth class

Solution:

Fraction of the whole athletic field reserved for four fifth classes = [tex]\frac{1}{6}[/tex]

So, fraction of the whole athletic field reserved for each fifth class = [tex]\frac{1}{4}(\frac{1}{6})=\frac{1}{24}[/tex]

Answer:

C) Integumentary, nervous, muscular

Explanation:

When a human body touches a hot stove , our sense organ which is integumen first of all receives the impulse of heat . The impulse is transformed into electrical signal which is transmitted to brain which is a part of nervous system . Then brain processes it and command signal is sent to muscle of hand to move it away from that place . Hence the order is

Integumentary, nervous, muscular .

Answer:

There are several roles of HCl in the digestive system. Some of them are as follows:

Answer:

Dissociated state is the predominant one

Explanation:

When a molecule with pKa of 4.52 is in an aqueous solution at pH = 4.0, follows the H-H equation, thus:

pH = pKa + log₁₀ [A⁻] / [HA]

Where [A⁻] is the dissociated state and [HA] represents the protonated state

Replacing:

4.0 = 5.2 + log₁₀ [A⁻] / [HA]

-1.2 = log₁₀ [A⁻] / [HA]

0.063 =  [A⁻] / [HA]

[HA]  = 16 [A⁻]

That means you have 16 times more [HA] than [A⁻] and the dissociated state is the predominant one

Answer:

The hardness is more than 2.5. Hope this helps.

Answer:

The hardness is more than 2.5.

Explanation:

Answer:

.01

Explanation:

H30+=10^-pH

- Hope that helps! Please let me know if you need further explanation.

Answer:B

Explanation:

Answer:

The second one

Explanation:

Because not only did I take a castle learning in this today but c2h4 has 6 covalent bonds

There are several types of molecules that have multiple bond. A molecule of which compound has a multiple covalent bond is C2H4.

Covalent bonding is the sharing of one or more electron pairs. In many covalent bonding situations,

Multiple chemical bonds exist when there is more than one electron pair that is being shared.

A nitrogen atom often fill its octet by sharing three electrons with another nitrogen atom thereby creating three covalent bonds.

Multiple bonds are commonly found in organic compound and they have carbon molecules.

Learn more from

https://brainly.com/question/4985972

Answer:

A chemical reaction is a process in which one or more substances, also called reactants, are converted to one or more different substances, known as products. ... A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Explanation:

Hopefully this is what you needed

Answer:

Explanation:

Hello!

a)

You have an integral membrane protein (Bacteriorhodopsin) that uses solar energy to pump protons out of the cell against its electrochemical gradient.

To calculate the energy needed by the protein to pump one molecule out of the cell you need to apply the free energy difference equation for a charged molecule:

ΔG= 2.303RTlog₁₀[tex](\frac{[H^+]out}{[H^+]in})[/tex]+zFΔV

Where

ΔG= free energy difference per molecule transferred from the inside to the outside

R= gas constant 8.315*10⁻³ kJ/mol

T= Temperature in Kelvin (273.15 + TºC)

z= Valency of the ion (ej Na⁺ is z= +1 and Cl⁻ is z= -1)

F= Faraday constant 96.5 kJ/V*mol

ΔV= membrane potential (Volts)

The information you have is:

Intracellular pH= 9.4

Extracellular pH= 6.4

ΔV= 120 mV

Temperature 27ºC

Using the values of pH you can calculate the intracellular and extracellular proton concentrations:

Remember the pH of a solution is calculated as pH=-log[H⁺] so if you reverse the logarithm, you'll find the concentration of protons:

b= logₐ C ⇒ C= aᵇ

[H⁺]intracelular= 10⁻⁹'⁴

[H⁺]extracelular= 10⁻⁶'⁴

Now you need to match the units of the temperature and electrical gradient to the ones in the equation:

The temperature needs to ve in Kelvin: T= 273.15 + 27ºC= 300.15K

The electrical gradients need to be in Volts: ΔV= 120 mV= 0.12V

Now you can replace the data in the formula and calculate how much energy is needed to pump one proton outside the cell:

ΔG= 2.303RTlog₁₀[tex](\frac{[H^+]out}{[H^+]in})[/tex]+zFΔV= 2.303*( 8.315*10⁻³ kJ/mol)*300.15K*log[tex](\frac{10^{-6.4}}{ 10^{-9.4}} )[/tex]+(+1)*96.5 kJ/V*mol*0.12V= 28.82 kJ/mol

It costs 28.82 kJ/mol to pump one mole of H⁺ outside the cell.

b)

To synthesize one molecule of ATP the ATP synthase uses the electrical gradient produced by the spontaneous pass of protons through the membrane. This process is called the proton-motive force.

The ATP synthase consists of two subunits F₀ and F₁ with a rotational motor mechanism that allows it to produce and release ATP.

F₁ has the subunits α, β, σ, γ, ε in charge of synthesizing ATP

F₀ is a proton pore, made of 3 subunits a, b and c. 6 subunits c make up the transmembrane ring in charge of rotation, this ring is connected to the subunits γ and ε. Each time a proton passes, it makes the ring rotate which makes the subunits γ rotate.

Each time the subunit γ rotates 360º, 3 ATP molecules are synthesized and freed. A full rotation of γ means that the c-ring also made a full rotation (for this you need one proton per subunit)

If the ring has 6 c-subunits and, then each ATP molecule needs 6/3= 2 protons to need to pass for each ATP molecule.

I hope this helps!

Answer:

the motion of gravity

Explanation:

Answer:

its c

Explanation

advhuosijoklxcmnjdabsuhggggabciaciudeifweingivg eygerigsygfe97rsghisdcvhbsduigwiugfu9uigdgiurfgyisdgfsdgfegiygewifgsdygfewusgfuyesigf7wgfiesgfiusgdfies

Answer:

Solute

Explanation

A substance that gets dissolved to create a solution is best described as to as

Answer:

Ionic bonds

Explanation:

It rymes.  haha i dont even know how to spell it! ;)