Which one of these is an example of a physical change?

A. sugar dissolving in warm water.

B. iron rusting in the presence of moist air.

C. wood burning in the presence of oxygen.

D. baking soda reacting with acid to form with acid to form a gas.

Answers

Answer 1
Hey there!

The correct answer to your question is option A.

Sugar dissolving in warm water is an example of a physical change.
This is because sugar dissolving in the water does not create a substance or material. All of the other options are examples of chemical changes, because they eventually become a substance/material.

Hope this helps you.
Have a great day!

Related Questions

Part a ammonia can be produced via the chemical reaction n2(g)+3h2(g)⇌2nh3(g) during the production process, the production engineer determines the reaction quotient to be q = 3.56×10−4. if k = 6.02×10−2, what can be said about the reaction? view available hint(s) ammonia can be produced via the chemical reaction during the production process, the production engineer determines the reaction quotient to be = 3.56×10−4. if = 6.02×10−2, what can be said about the reaction? the reaction has reached equilibrium. the reaction is not at equilibrium and will proceed to the left. the reaction is not at equilibrium and will proceed to the right. the reaction is not at equilibrium, but it is not possible to determine whether the reaction needs to proceed right or left to reach equilibrium. submit

Answers

The correct answer is that the reaction is not at equilibrium and will proceed to the right.  as Q < Kc
To understand the answer to this question it's mainly a comparison between the Q and Kc value

when we have Kc= [NH3]^2/[N2][H2]^3 = 6.02x10^-2 
and the Q value = 3.56x10^-4 
SO here by comparing Kc value to Q value, we found that 
1) Q < Kc :
in this case, the reaction will move towards the right to increase the products and decrease the reactants, So the reaction is preferring a forward reaction to reach the equilibrium.  
2) but when Q> Kc :
the reaction will move towards the left to increase the reactants and decrease the products, So the reaction is preferring a reverse reaction to reach the equilibrium.
3) in case of Q= Kc :
in this case, the reaction is in the equilibrium and don't go right or left shift and the forward and reverse reactions are proceeding at the same rate.

So by comparing our Kc & Q in the question, we found that Q<Kc
∴ the answer is that the reaction is not in equilibrium and will proceed to the right.



name two fluid technologies that make use of water

Answers

Answer:

Fire extenguisher and refrigerator

Explanation:

Refrigerator : There are 5 basic components in refrigeration I.e. fluid refrigerant, a compressor which controls the flow of refrigerant; the condensor coil( on the outside of the fridge), evaporation coils( on the inside of the fridge) and something calls an expansion device.

The compressor constricts the refrigerant vapour,raising its pressure and pushes it in the coils on the outside of the refrigerator.When the hot gas in the coils meets the cooler air temperature of the kitchen it becomes a liquid.Now in the liquid form at high pressure, the refrigerant cools down as it flows into the coils inside the freezer and the fridge.The refrigerant absorbs the heat inside the fridge cooling down the air.Last the refrigerant evaporates to a gas then flows back to the compressor where the cycle starts all over.

Fire Extinguishers: Water performs two functions; its conversion tosteam absorbs the heat, and the steam displaces the air from the vicinity of the flame. Many siimple fire extinguishers  are quipped with hand pumps or sources of compressed gas to propel water through the nozzle.

Final answer:

Hydraulic systems and water turbines are two fluid technologies that make use of water. Hydraulic systems use water or other fluids to transmit force or energy, while water turbines use the flow of water to generate mechanical energy and produce electricity.

Explanation:

Two fluid technologies that make use of water are hydraulic systems and water turbines.

Hydraulic systems: These systems use water or other fluids to transmit force or energy. They are commonly used in heavy machinery, such as bulldozers and cranes. The force applied to a small piston can be amplified to produce a much larger force on a larger piston. This is done by Pascal's law, which states that a change in pressure of an enclosed fluid is transmitted uniformly in all directions.Water turbines: These devices use the flow of water to generate mechanical energy, which is then converted into electrical energy. Water turbines are often used in hydroelectric power plants, where the force of flowing water is used to turn the blades of the turbine, which in turn spins a generator to produce electricity.

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A sealed beaker of what you are told is aqueous nickel sulfide was given to you by the local chemist and you put it on the window sill. after a few days, you notice that the mixture is getting thick toward the bottom. what is the nature of the initial nickel sulfide mixture, assuming that the temperature on the sill remained approximately constant?

Answers

Answer is: the nature of the initial nickel sulfide mixture is a suspension.
Suspension is a heterogeneous mixture (solute particles do not dissolve), that contains solid particles (in this example nickel sulfide or NiS) sufficiently large for sedimentation.  The internal phase (solid nickel sulfide) is dispersed throughout the external phase (water).

The nature of the initial nickel sulfide mixture : suspension

Further explanation

A pure substance can be an element or compound.

The element is a single substance that cannot be broken down anymore or the simplest substance.

While the compound is a pure substance that is formed from a combination of two or more elements through chemical reactions and has a constant chemical ratio.

A mixture is a combination of two or more single substances. The properties of the mixture component are not lost / unchanged as in compounds.

The mixture can be divided into a homogeneous mixture if the composition/ratio of each substance in the mixture is the same and heterogeneous mixture if the ratio of the composition of the substances is not the same (can be varied) in each place.

Mixtures can also be divided into solutions, suspensions, and colloids based mainly on the size of the particles

Homogeneous mixture = Solution

Heterogeneous mixture = suspension, and

The mixture is located between suspension and solution = Colloid

The solution is a mixture of two or more substances consisting of a solute and a solvent. The particle size of the solution is very small, less than 1 nm, it cannot be distinguished between the solute and its solvent medium. Substances in a solution cannot be separated through filtering.

The solution has the same composition in each of its parts.

Suspensions are rough mixes and are heterogeneous. Particle size more than 100 nm.

The mixture is a murky solution, but it gradually separates due to the influence of gravity (undergoes precipitation). Suspension can be separated by filtering.

Colloids are mixtures of dispersed particles and dispersing particles. The size of colloidal particles lies between 1 nm - 100 nm

colloid mixtures cannot be separated through ordinary filtering, but rather with ultrafilters.

Aqueous nickel sulfide (NiS) has been deposited after being placed several days, so it can be classified into a mixture of suspensions

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A heterogeneous mixture

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a homogeneous mixture

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an example of a physical change

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Carbon dioxide gas and liquid water form solid glucose (C6H12O6) and oxygen gas during photosynthesis. Chlorophyll absorbs light in the 600-700 nm region.

a) Write a balanced thermochemical equation for the formation of 1.00 mol of glucose.
... I know that it goes like this: 6CO2(g)+6H2O(l)-->C6H12O6(s)+6O2(g)... this is already balanced but not yet considered a "thermochemical equation"

b) What is the minumum number of photons with Y=680 nm needed to form 1.00 mol of gluscose?

Answers

a)

A thermochemical equation is the one which includes heat of the reaction

Heat of reaction is also known as "enthalpy of reaction" ( ΔH rxn) and it is the amount of heat absorbed or evolved during the reaction.

The balanced equation for the reaction can be written as

[tex] 6 CO_{2}(g)+ 6 H_{2}O(l)\rightarrow C_{6}H_{12}O_{6}(s)+ 6O_{2}(g) [/tex]

Let us find ΔH rxn for the given reaction

We need heat of formation of the reactants and products. We will use standard reference table to get this data.

From standard table of enthalpies, we have

[tex] H_{f}^{0} Glucose (s) = -1273.3kJ/mol [/tex]

[tex] H_{f}^{0} CO_{2}(g)= -393.5 kJ/mol [/tex]

[tex] H_{f}^{0} H_{2}O(l)= -285.8 kJ/mol [/tex]

[tex] H_{f}^{0} O_{2}(g)= 0 [/tex]

Enthalpy of reaction can be calculated using following formula

[tex] \bigtriangleup H^{0} _{rxn}= \sum H_{f} (products) - \sum H_{f} ( reactants) [/tex]

Let us plug in the standard enthalpy of formation values we found out from reference table.

[tex] \bigtriangleup H^{0} _{rxn}= [-1273.3 kJ.mol + 0]- [6\times (-393.5kJ/mol) + 6\times (-285.8 kJ/mol)] [/tex]

[tex] \bigtriangleup H^{0} _{rxn}= [-1273.3 kJ.mol]- [-4075.8kJ/mol)] [/tex]

[tex] \bigtriangleup H^{0} _{rxn}= -1273.3 kJ.mol+ 4075.8kJ/mol [/tex]

[tex] \bigtriangleup H^{0} _{rxn}= 2802.5 kJ/mol [/tex]

The thermochemical equation for the given reaction can be written as

[tex] 6 CO_{2}(g)+ 6 H_{2}O(l)\rightarrow C_{6}H_{12}O_{6}(s)+ 6O_{2}(g).....\bigtriangleup H_{rxn} = 2802.5 kJ/mol [/tex]

b)

The wavelength of the light absorbed by chlorophyll is 680 nm.

Let us find the energy of one photon having wavelength = 680 nm.

The relationship between energy and wavelength is given by the following equation.

[tex] E = \frac{h\times c}{\lambda } [/tex]

Where E = energy of the photon

h = Plank's constant = 6.626 x 10⁻³⁴ J.s

c = velocity of light = 3.00 x 10⁸ m/s

λ = wavelength of light = 680 nm.

We need the wavelength in meters.

[tex] 680 nm\times \frac{1 m}{10^{9}nm}= 6.80 \times 10^{-7}m [/tex]

λ = 6.80 x 10⁻⁷ m

Let us find E now.

[tex] E = \frac{6.626\times 10^{-34}J.s\times 3.00 \times 10^{8}m/s}{6.80 \times 10^{-7}m} [/tex]

[tex] E = \frac{1.9878 \times 10^{-25}}{6.80\times 10^{-7}}J [/tex]

[tex] E = 2.92 \times 10^{-19}J [/tex]

Let us convert this to kJ.

[tex] 2.92 \times 10^{-19}J \times \frac{1kJ}{1000 J}= 2.92 \times 10^{-22}kJ [/tex]

Energy of 1 photon = 2.92 x 10⁻²² kJ

The total amount of energy absorbed during the photosynthesis reaction is 2802.5 kJ

Number of photons = Total energy absorbed / Energy of 1 photon

Number of photons = [tex] \frac{2802.5 kJ}{2.92 \times 10^{-22}kJ} [/tex]

Number of photons = 9.60 x 10²⁴

The minimum number of photons needed to form 1.0 mol of glucose is 9.60 x 10²⁴

oxidation states of N2 + 3H2 --> 2NH3

Answers

True because n on both sides are 2 and the hydrogen on both sides are 6

Give the empirical formula of a compound that contains 11.6g iron and 5.01 g of oxygen

Answers

Fe2O3 is the answer.

Good luck :)

Two teaspoons of salt are added to a glass of water which is then stirred until no more salt grains can be seen. Two more teaspoons are added and stirring is continued, but the salt grains are still evident in the glass and settle to the bottom. After the addition of the last two teaspoons of salt the solution is ___________________________.
nonpolar
polar
saturated
unsaturated

Answers

Hello!

After the addition of the last two teaspoons of salt, the solution is saturated

A solution is saturated when it has the highest amount of solute (in this case the salt) that the solvent (in this case the water) can dissolve at that pressure and temperature. 

Visually, a saturated solution can be detected when the adding of more solute results in the settling of solute grains (in this case salt) at the bottom of the container, because the solvent couldn't dissolve them at that pressure and temperature. That's why we can say that the solution is saturated.

Have a nice day!  

Answer: C

Explanation: I got it right

Co(g)+h2o(g)⇌co2(g)+h2(g) kp=0.0611 at 2000 k a reaction mixture initially contains a co partial pressure of 1320 torr and a h2o partial pressure of 1760 torr at 2000 k. calculate the equilibrium partial pressure of co2.

Answers

Final answer:

We use the expression for Kp in terms of partial pressures, set up an equation incorporating the given initial pressures and the changes in pressure that occur as the reaction proceeds, and solve that equation to find the equilibrium partial pressure of CO2.

Explanation:

To answer this question, we need to use the expression for the equilibrium constant (Kp) in terms of partial pressures. Kp is defined as the ratio of the products of the partial pressures of the products, each raised to their stoichiometric coefficients in the balanced chemical equation, to the product of the partial pressures of the reactants, each raised to the power of their stoichiometric coefficients. Based on this, the expression is:

Kp = (pCO2 * pH2) / (pCO * pH2O)

where pCO, pH2O, pCO2 and pH2 are the equilibrium partial pressures of CO, H2O, CO2 and H2 at equilibrium, respectively. We know that initially, the partial pressure of CO2 and H2 is 0 because the reaction has not yet occurred. Also, the initial partial pressures of CO and H2O are given as 1320 torr and 1760 torr respectively.

As reaction proceeds to the right, the pressures of CO and H2O will decrease while that of CO2 and H2 will increase. Let's assume the decrease in the pressures of CO and H2O is by x.

Therefore, at equilibrium:

pCO = 1320 - xpH2O = 1760 - xpCO2 = xpH2 = x

So, plug these values into the Kp expression we get:

0.0611 = (x*x) / {[1320 - x]*[1760 - x]}

Solving this quadratic equation will give the value of x.

Substituting 'x' in pCO2 = x will give us the equilibrium partial pressure of CO2.

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Final answer:

The equilibrium partial pressure of CO2 in a chemical reaction can be calculated using an ICE table and the given Kp value in the application of Le Chatelier's principle.

Explanation:

The subject of this question is the calculation of the equilibrium partial pressure of CO2 in a chemical reaction according to Le Chatelier’s principle. We first identify the given Kp value and initial partial pressures for CO and H20. Using the equation for the reaction, CO(g) + H2O(g) ⇌ CO2(g) + H2(g), we can create an ICE (Initial, Change, Equilibrium) table to track changes in the partial pressures during the reaction. As the reaction proceeds, the concentrations of CO and H2O decrease while those of CO2 and H2 increase until equilibrium is reached. The changes for CO and H2O are negative while those for CO2 and H2 are positive. Using the equilibrium expressions and the given Kp value, we can solve for the change and add this to the initial concentrations to get the equilibrium concentrations.

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A solution of hydrochloric acid is mixed with an equal volume solution of barium hydroxide. When pH paper is inserted into the resulting solution, the pH was determined to be 7.0. If the initial concentration of the hydrochloric acid solution was 0.5 M, what is the concentration of the barium hydroxide solution?

Please explain your steps and balanced equation.

Answers

the balanced equation for the reaction between Ba(OH)₂ and HCl is ;
Ba(OH)₂ + 2HCl ----> BaCl₂ + 2H₂O
When equal volumes of both acid and base are added, the pH is 7 which means its neutral. 
This means that the H⁺ ions and OH⁻ are equal and they have neutralised each other. All the ions have reacted to form water molecules.
Dissociation of base and acid are as follows;
Ba(OH)₂ ---> Ba²⁺ + 2OH⁻
1 mol of Ba(OH)₂ dissociates to 2 mol H⁺
HCl ---> H⁺ + Cl⁻
n moles of HCl give out n mol of H⁺ ions
H⁺ = OH⁻ which is why solution is neutral
then OH⁻ moles present are n  mol 
then Ba(OH)₂ moles present should be n/2 mol
molarity of HCl = 0.5 mol/L
since volumes are equal number of moles are directly proportional to molarity 
molarity of Ba(OH)₂ = 0.5/2 = 0.25 M

Why is the percentage of food eaten a good number to use ? Explain

Answers

To understand that you have to balance each food you intake in your body. Balancing your food is not only useful to make you stay fit but it can enhance your mental and physical health. With the use of proper diet, you will go on to your everyday routine without feeling uncomfortable.

Which of the following indicates that an exothermic reaction has occurred? Temperature increases Heat is absorbed Salt is produced Water is formed

Answers

Answer: Option (a) is the correct answer.

Explanation:

A chemical reaction where heat energy is absorbed by the reactant molecules is known as an endothermic reaction.  

For example, [tex]A + B + Heat \rightarrow AB[/tex]

The value of [tex]\Delta H[/tex] = +ve for an endothermic reaction.

In an endothermic reaction, heat being absorbed is utilized to break the bonds. Therefore, temperature of the system decreases.

On the other hand, a chemical reaction in which heat energy is released by the reactant molecules is known as an exothermic reaction.  For example, [tex]C + D \rightarrow CD + Heat[/tex] is an exothermic reaction.

Generally, there occurs an increase in temperature of the substance or system because of the evolution of heat during an exothermic reaction.

Thus, we can conclude that temperature increases indicates that an exothermic reaction has occurred.

Answer:

Temp increases

Explanation:

The ka value for acetic acid, ch3cooh(aq), is 1.8× 10–5. calculate the ph of a 2.20 m acetic acid solution.

Answers

Answer is: pH value of acetic acid is 2.2.
Chemical reaction: CH₃COOH(aq) ⇄ CH₃COO⁻(aq) + H⁺(aq).
Ka(CH₃COOH) = 1,8·10⁻⁵.
c(CH₃COOH) = 2,2 M
[CH₃COO⁻] = [H⁺] = x.
Ka = [CH₃COO⁻] · [H⁺] / [CH₃COOH].
1,8·10⁻⁵ = x² / (2,2 M - x).
Solve quadratic equation: x = [H⁺] = 0,0063 M.
pH = -log[H⁺].
pH = -log(0,0063 M).
pH = 2,2.

Calculate the [h+] in a solution that has a ph of 9.88.

Answers

pH scale is used to determine how acidic, basic or neutral a solution is.
pH can be calculated using the Hydrogen ion concentration.
pH is calculated using the following formula
pH = -log [H⁺]
[H⁺] can be calculated knowing the pH
[H⁺] = antilog(-pH)
[H⁺] = 1.32 x 10⁻¹⁰ M

The concentration of  H⁺ ions present in the solution that has a pH of 9.88 is 1.3 × 10⁻¹⁰M.

What is pH?

pH of any solution is define as the negative logarithm of the concentation of H⁺ ions present in the solution and it will be represented as:

pH = -log[H⁺]

After removing log equation becomes,

[H⁺] = [tex]10^{-pH}[/tex]

Given value of pH = 9.88

On putting this value of above equation we get,

[H⁺] = [tex]10^{-9.88}[/tex]

[H⁺] = 1.3 × 10⁻¹⁰M

Hence the concentration of H⁺ ions is 1.3 × 10⁻¹⁰M.

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Please help!
Explain what happens to the pitch of a cell phone ring when the amplitude of a sound wave increases. Justify your reasoning using complete sentences and key vocabulary.

Answers

Pitch is sometimes defined as the fundamental frequency of a sound wave. For most practical purposes, this is fine, and pitch and frequency can be thought of as equivalent. On the other hand, for most practical purposes, amplitude can be thought of as volume.

However, technically, pitch and volume are human perceptions. Thus, our perception of pitch and volume are not solely based on frequency and amplitude respectively, but are based on a combination of both. Frequency overwhelming dictates perceived pitch, but amplitude also does have some small, small effect on our pitch perception, especially when it is very large. For example, a very loud sound can have a different perceived pitch than you would predict from its frequency alone.

Hope that helps!

Marie and Calvin dissolved 10 grams of KNO3 in 100 grams of water at 25oC. Next they added 5 grams more. Calvin told Marie that they could continue to add solute until they reached 40 grams because the solution was still

Answers

Hello!

Calvin told Marie that they could continue to add solute until the reached 40 grams because the solution was still unsaturated.

Unsaturated solutions are those in which the solvent (in this case water) can still dissolve more solute (in this case KNO₃) at the given pressure and temperature. This can be seen visually when adding more solute doesn't result in the presence of grains of solids that settle in the bottom of the flask. That happens because the rate of dissolving is higher than the rate of crystallization. 

Have a nice day!

Of the molecules AlC l 3 and AlB r 3 , which has bonds that are more polar?

Answers

The electronegativity difference of the Al and Cl atoms in AlCl₃ molecule is 1.55 while the electronegativity difference of the Al and Br atoms in AlBr₃ is 1.35

The electronegativity difference of atoms in AlCl₃ molecules is as follows:
3.16 - 1.61 = 1.55
The electronegativity difference of atoms in AlBr₃ molecules is as follows:
2.96 - 1.61 = 1.35

- Both the molecules have a significant amount of difference in the electronegativity of atoms → This shows that both molecules have polar character.

- But, the electronegativity difference in molecule AlCl₃ is 1.55, which is greater than 1.35 of the AlBr₃.

Therefore AlCl₃ is more polar molecule than AlBr₃  

Final answer:

AlCl₃ has stronger polar bonds than AlBr₃ due to chlorine's higher electronegativity. The overall polarities of these compounds would also consider their similar trigonal planar structures.

Explanation:

Of the molecules AlCl₃ and AlBr₃, AlCl₃ has more polar bonds. Bond polarity arises from the difference in electronegativity between the two atoms forming a bond. Chlorine (Cl) is more electronegative than Bromine (Br), hence, electrons in AlCl₃ are pulled towards Cl more than electrons in AlBr₃ are pulled towards Br. This makes the bonds in AlCl₃ more polar than those in AlBr₃.

In the context of a molecule being polar or nonpolar, apart from just electronegativity, we also need to consider the molecule's geometric structure. However, since both AlCl₃ and AlBr₃ have a similar structure (trigonal planar), influencing factors remain the bond polarities.

The two idealized extremes of chemical bonding: (1) ionic bonding—in which one or more electrons are transferred completely from one atom to another, and the resulting ions are held together by purely electrostatic forces—and (2) covalent bonding, in which electrons are shared equally between two atoms. Most compounds, however, have polar covalent bonds, which means that electrons are shared unequally between the bonded atoms. Figure 3.4.4 compares the electron distribution in a polar covalent bond with those in an ideally covalent and an ideally ionic bond. Recall that a lowercase Greek delta ( δ

) is used to indicate that a bonded atom possesses a partial positive charge, indicated by  δ+

, or a partial negative charge, indicated by  δ−

, and a bond between two atoms that possess partial charges is a polar bond.

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This solution contains equal concentrations of both hf(aq) and naf(aq). write the proton transfer equilibrium (net ionic) reaction that includes f– as a reactant. include states of matter.

Answers

Net ionic reaction for the solution containing equal concentrations of both HF(aq) and NaF(aq) is as follow:
F⁻(aq) + H₂O(l) ⇄ HF(aq) + OH⁻(aq)

In a reaction of NaF and H₂O, NaOH and HF is produced.

The reaction can be shown as follows:

HF(aq.) + OH⁻(aq.) ----->F⁻(aq.) + H₂O(l)

Or it can be shown as below:

Here the reactants are: NaF, H₂O

While the product is: NaOH, HF

So the reaction in ionic can be shown as:

HF(aq.) + OH⁻(aq.) ----->F⁻(aq.) + H₂O(l)

So the reaction can be that includes the states of matter too can be:

HF(aq.) + OH⁻(aq.) ----->F⁻(aq.) + H₂O(l)

2. In the reaction NO + NO2 ⇌ N2O3, an experiment finds equilibrium concentrations of [NO] = 3.8 M, [NO2] = 3.9 M, and [N2O3] = 1.3 M. What is the equilibrium constant Kc for this reaction?
A. 0.064
B. 0.088
C. 0.114
D. 0.193

Answers

Kc= concentration  of  product  divided  by  concentration   of  reactant
NO +  NO2  ---->  N2O3

Kc =(N2O3)  /  (No)(NO2)

Kc= ( 1.3  )/{ (3.9)(3.8) }

Kc=0.088 (  answer  B)

Answer:

B. 0.088

Explanation:

I got it right

liam uses a machine that counts waves on a metal cable. The machine counts 25 waves in 2 seconds. what is the frequency of the wave?

Answers

Frequency is defined as the number of waves per second. In this machine 25 waves pass in one second.
We need to calculate the number of waves that pass a particular point during one second.
During 2 seconds -25 waves
Therefore in one second - 25/2 = 12.5 waves/s.
1 wave per second has the unit Hertz (Hz)
Therefore answer is 12.5 Hz

Final answer:

The frequency of the waves on the metal cable that Liam is using is calculated by dividing the number of waves, which is 25, by the time period over which they are counted, which is 2 seconds. This results in a frequency of 12.5 Hertz (Hz).

Explanation:

The question asks us to determine the frequency of a wave given the number of waves and the time it took for those waves to be counted. In this case, Liam's machine counts 25 waves in 2 seconds. Frequency is the number of waves that pass a given point in one second, and it is measured in Hertz (Hz).

To calculate the frequency, you divide the number of waves by the period. Using the information from the question:

Count of waves passing by 25 wavesTime period: 2 seconds.

Frequency (f) = Number of waves / Time (T) = 25 waves / 2 s = 12.5 Hz. Hence, the frequency of the waves on the metal cable is 12.5 Hertz.

which is a dangerous thing to do when working with flames in a laboratory?

Answers

In laboratories, there are many different types of substances and chemicals. It is dangerous to work with flames in a laboratory because there could very likely be flammable or explosive material in the laboratory that could harm assistants and researchers.
it can be chemicals, flames, unknown substances
those are dangerous

Which chemical agent will you use to modify the frog heart rate?

Answers

There are different chemical agents which are used to study the heart rate of frog. Generally Ringer's solution is used to study frog's heart simulation. At different temperature, frogs heart speeds up or slows down while using Ringer's solution at experiment. Ringer's solution is mixture of salt solution which comprises of NaCl, KCl, CaCl2 and Na2CO3. Sometimes other chemicals like MgCl or antibiotics are also used as addition in Ringer's solution. 
This solution is chiefly used to study in vitro experiments on organs and tissues like frog's heart.

Ringer's solution at 23 degree Celsius for normal heart rate
Ringer's solution at 32 degree Celsius, heart rate speed up and 
Ringer's solution at  5 degree Celsius, heart rate slows down.

other chemicals also have significant effect in heart rate,
For example, Calcium ion in excess will slow down the heart rate, Atropine increases heart rate and digitalis slows down the heart rate.

Write balanced complete ionic equation for the reaction AgNO3(aq)+KCl(aq)→AgCl(s)+KNO3(aq).

Answers

Explanation:

A balanced equation is an equation in which number of reactants equal the number of products.

The given equation is as follows.

         [tex]AgNO_{3}(aq) + KCl(aq) \rightarrow AgCl(s) + KNO_{3}(aq)[/tex]

Therefore, the ionic equation for the given reaction is as follows.

  [tex]Ag^{+}(aq) + NO^{-}_{3}(aq) + K^{+}(aq) + Cl^{-}(aq) \rightarrow AgCl(s) + K^{+}(aq) + NO^{-}_{3}(aq)[/tex]     ....... (1)

Now, cancel [tex]NO^{-}_{3}(aq)[/tex] and [tex]K^{+}[/tex] from both left and right side of the equation (1).

Hence, the net ionic equation will be as follows.

     [tex]Ag^{+}(aq) + Cl^{-}(aq) \rightarrow AgCl(s)[/tex]  

Final answer:

For the reaction of AgNO3(aq)+KCl(aq)→AgCl(s)+KNO3(aq), the balanced complete ionic equation is Ag+ (aq) + NO3- (aq) + K+ (aq) + Cl- (aq) → AgCl(s) + K+ (aq) + NO3- (aq), which shows the ions involved and distinguishes between the reacting ions forming the precipitate, and the spectator ions.

Explanation:

The question is asking for a balanced complete ionic equation, which emphasizes the ions in a chemical equation. For the reaction of AgNO3(aq)+KCl(aq)→AgCl(s)+KNO3(aq), the balanced complete ionic equation would be written as:

Ag+ (aq) + NO3- (aq) + K+ (aq) + Cl- (aq) → AgCl(s) + K+ (aq) + NO3- (aq)

In this equation, Ag+ and Cl- are the ions reacting to form the precipitate AgCl(s), while K+ and NO3- are the spectator ions, which exist in the same form on both reactant and product side of the equation.

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Consider these reactions, where M represents a generic metal. 2M(s)+6HCl(aq)⟶2MCl3(aq)+3H2(g)ΔH1=−556.0 kJ HCl(g)⟶HCl(aq) ΔH2=−74.8 kJ H2(g)+Cl2(g)⟶2HCl(g) ΔH3=−1845.0 kJ MCl3(s)⟶MCl3(aq) ΔH4=−342.0 kJ Use the given information to determine the enthalpy of the reaction 2M(s)+3Cl2(g)⟶2MCl3(s)

Answers

Chemical reaction 1: 2M(s)+6HCl(aq)⟶ 2MCl3(aq)+3H2(g); ΔH1=−556.0 kJ. Chemical reaction 2: HCl(g) ⟶ HCl(aq); ΔH2=−74.8 kJ.
Chemical reaction 3: H2(g)+Cl2(g) ⟶ 2HCl(g); ΔH3=−1845.0 kJ
Chemical reaction 4: MCl3(s) ⟶ MCl3(aq); ΔH4=−342.0 kJ.
Chemical reaction 5: 2M(s)+3Cl2(g) ⟶ 2MCl3(s); ΔH5 = ?.ΔH5 = ΔH1 + 6·ΔH2 + 3·ΔH3 - 2·ΔH4.
ΔH5 = -550 kJ + 6·(-74,8 kJ) + 3·(-1845 kJ) - 2·(-342 kJ).
ΔH5 = -550 kJ - 448,8 kJ - 5535 kJ + 684 kJ.
ΔH5 = -5849,8 kJ.

The enthalpy of formation of [tex]\rm MCl_3[/tex] will be -5849 kJ.

The given reactions represent:

Enthalpy of reaction of M with HCl = [tex]\rm \Delta H_1[/tex] = -556 kJ

Enthalpy of sublimation of HCl = [tex]\rm \Delta H_2[/tex] = -74.8 kJ

Enthalpy of HCl formation = [tex]\rm \Delta H_3[/tex] = -1845 kJ

Enthalpy of sublimation of [tex]\rm MCl_3\;=\;\Delta H_4[/tex] = -342.0 kJ

The enthalpy of formation of [tex]\rm MCl_3[/tex] will be: [tex]\rm \Delta H_5[/tex]

[tex]\rm \Delta H_5[/tex] = [tex]\rm \Delta H_1\;+\;6\;\times\;\Delta H_2\;+\;3\;\times\;\Delta H_3\;-\;2\;\times\;\Delta H_4[/tex]

= -550 + 6 (-74.8) + 3 (-1845) - 2 (342)

= -5849 kJ.

The enthalpy of formation of [tex]\rm MCl_3[/tex] will be -5849 kJ.

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The part of the flower that becomes a fruit to protect the seeds is the _______. stigma style ovary anther

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ovaryovaryovaryovary

ovary is your answer dude

A 0.465 g sample of an unknown compound occupies 245 ml at 298 k and 1.22 atm. what is the molar mass of the unknown compound?
a.26.3 g/mol
b.33.9 g/mol
c.12.2 g/mol
d.38.0 g/mol
e.81.8 g/mol

Answers

we can find the number of moles of gas using the ideal gas law equation
                                                                                                 
PV = nRT
                                                                                                 
where P - pressure - 1.22 atm
                                               
V - volume - 0.245 L
                                                                                               
n - number of moles
                                                                                               
R - gas constant - 0.08206 L.atm/mol.K
                                               
T - temperature - 298 K
                                                                                               
substituting the values in the equation
                                                   
1.22 atm x 0.245 L = n x 0.08206 L.atm/mol.K x 298 K
                                               
n = 0.0122 mol
                                                                                               
molar mass of compound = mass present / number of moles therefore molar mass = 0.465 g / 0.0122 mol = 38.1 g/mol
the answer is d) 38.0 g/mol

Answer: Option (d) is the correct answer.

Explanation:

It is know that for an ideal gas PV = nRT

where     P = pressure

               V = volume

               n = number of moles = [tex]\frac{mass}{molar mass}[/tex]

                R = gas constant = 0.082 [tex]L atm K^{-1} mol^{-1}[/tex]

                T = temperature

Therefore, put the given values in the formula above as follows.

                   PV = nRT

or,               PV = [tex]\frac{mass}{molar mass}RT[/tex]

               [tex]1.22 atm \times 0.245 L = \frac{0.465 g}{molar mass} \times 0.082 L atm K^{-1} mol^{-1} \times 298 K[/tex]

                molar mass = 38.12 g/mol

                                    = 38.0 g/mol (approx)

Therefore, we can conclude that the molar mass of the unknown compound is 38.0 g/mol.

To study Earth’s interior, geologists often rely on indirect methods, such as evidence from fossils. true or false

Answers

Answer:

the answer is false, the person that said true is incorect.

Explanation:

Answer: FALSE

Explanation:To study Earth’s interior, geologists often rely on indirect methods, such as evidence from fossils.

Write balanced chemical equations for the two ionization steps of sulfuric acid

Answers

Hello!

Sulfuric acid (H₂SO₄) is a strong diprotic acid. "Diprotic" means that the acid donates 2 protons when dissociating in water to form ions. This happens in a series of two steps which are described below. The first reaction is basically a complete reaction while the second one is an equilibrium:

H₂SO₄(aq) + H₂O(l) → HSO₄⁻(aq) + H₃O⁺(aq)

HSO₄⁻(aq) + H₂O(l) ⇄ SO₄⁻²(aq) + H₃O⁺(aq)

Have a nice day!
Final answer:

Sulfuric acid ionizes in two steps, each releasing a hydrogen ion to form first the bisulfate ion and then the sulfate ion. The first is H2SO4 (aq) → H+ (aq) + HSO4- (aq) and the second is HSO4- (aq) → H+ (aq) + SO4^2- (aq).

Explanation:

The ionization of sulfuric acid (H2SO4) in water occurs in two steps. Each step involves the release of a hydrogen ion (H+), and the corresponding production of the hydronium ion (H3O+) is generally implied when the acid ionizes in aqueous solution.

First Ionization: H2SO4 (aq) → H+ (aq) + HSO4- (aq).This is the first ionization step where one hydrogen ion is released, creating the bisulfate ion (HSO4-).

Second Ionization: HSO4- (aq) → H+ (aq) + SO4^2- (aq). In the second ionization step, the bisulfate ion (HSO4-) releases a second hydrogen ion, resulting in the sulfate ion (SO4^2-).

Both of these equations are balanced chemical equations that depict the stepwise ionization of sulfuric acid and the formation of its conjugate bases.

Calculate the heat capacity, in joules per degree and in calories per degree, for 45.8 g of nitrogen gas. [heat capacity of n2(g)= 1.04j/g0c] [1 cal=4.184j]

Answers

Answer : The heat capacity in joules per degree Celsius and calories per degree Celsius is, [tex]47.6J/^oC[/tex] and [tex]11.4cal/^oC[/tex] respectively.

Explanation : Given,

Mass of nitrogen gas = 45.8 g

Heat capacity of nitrogen gas = [tex]1.04J/g^oC[/tex]

First we have to calculate the heat capacity in joules per degree Celsius.

As, 1 gram of nitrogen gas has heat capacity = [tex]1.04J/^oC[/tex]

So, 45.8 gram of nitrogen gas has heat capacity = [tex]45.8\times 1.04J/^oC=47.6J/^oC[/tex]

Thus, the heat capacity in joules per degree Celsius is [tex]47.6J/^oC[/tex]

Now we have to calculate the heat capacity in calories per degree Celsius.

As we are given the conversion:

[tex]1cal=4.184J\\\\1J=\frac{1}{4.184}cal[/tex]

So, the heat capacity of nitrogen gas = [tex]\frac{1}{4.184}cal\times 47.6\text{ per }^oC=11.4cal/^oC[/tex]

Thus, the heat capacity in calories per degree Celsius is [tex]11.4cal/^oC[/tex]

The heat capacity, in Joules per degree Celsius and in calories per degree Celsius are 47.632 J/g°C and 11.384 cal/g°C respectively.

Given the following data:

Mass of nitrogen gas = 45.8 gramsHeat capacity of nitrogen gas = 1.04 J/g°C

To find the heat capacity, in Joules per degree Celsius and in calories per degree Celsius:

By direct proportion:

1 gram of nitrogen gas = 1.04 J/g°C

45.8 grams of nitrogen gas = X J/g°C

Cross-multiplying, we have:

[tex]X = 45.8 \times 1.04[/tex]

X = 47.632 J/g°C.

Therefore, the heat capacity, in Joules per degree Celsius, for 45.8 grams of nitrogen gas is 47.632 J/g°C.

In calories per degree Celsius:

1 calorie = 4.184 Joules

Y calorie = 47.632 Joules

Cross-multiplying, we have:

[tex]Y \times 4.184 = 47.632\\\\Y = \frac{47.632}{4.184}[/tex]

Y = 11.384 cal/g°C.

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What is the pH of a solution of 0.750 M KH2PO4, potassium dihydrogen phosphate?

Answers

Final answer:

The pH of a 0.750 M KH₂PO₄ solution cannot be accurately determined without additional information such as the pKa value of the dihydrogen phosphate ion (H₂PO₄₋).

Explanation:

The pH of a solution of 0.750 M KH₂PO₄, potassium dihydrogen phosphate, depends on the acid dissociation constants of phosphoric acid (H₃PO₄), as KH₂PO₄ is its conjugate salt. Typically, to calculate the pH of such a solution, one would use the Henderson-Hasselbalch equation which relates the pH of a buffer solution to the pKa of the acid and the concentrations of the acid and its conjugate base.

However, because there is no other species like phosphoric acid or its other salts present to form a buffer system, and because H₂PO₄₋ (from dissociation of KH₂PO₄) is a weak acid, we may need to approach this problem differently.

Since the direct calculation of pH in this context isn't possible without additional information such as the pKa value of the dihydrogen phosphate ion (H₂PO₄⁻), and because the problem does not ask for assumptions to be made or provide a relevant pKa value, the task cannot be completed.

In practical applications, a pKa value would be required to use the Henderson-Hasselbalch equation, or for the weak acid formula: pH = -log[H⁺] where [H⁺] can be obtained through the equilibrium expression involving the dissociation constant (Ka) and the concentration of H₂PO₄⁻.

dentify which stage of the listening process is occurring in the following scenario.

Janie excitedly told her mom about a party her friend Reeve had invited her to. She promised that there would be adult supervision and begged to be allowed to go. Her mom hesitated and then said she wanted to talk to Reeve's parents first.

selecting

understanding

evaluating

responding

remembering

Answers

Final answer:

In this situation, the listening process stage being implemented is 'evaluating'. Janie's mom is assessing the details of the party and deciding about its validity and reliability, which indicates this stage.

Explanation:

In the given scenario, the stage of the listening process that is taking place is evaluating. The event happens as Janie's mom listens to Janie's account of the party and makes a judgment about it. It means she's weighing the information she has received and is deciding on its validity and reliability. After listening to the information, she makes an evaluation that requires her to speak to Reeve's parents first before making a decision. This is the evaluating stage, where she is assessing and judging the information she has received.

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