A solution is made by dissolving
42.3 g of potassium hydroxide
(KOH) in 329 g of water.
What is the molality of the solution?

Answer:

Approximately [tex]2.64\times 10^{20}[/tex] (assumption: wavelength [tex]525\; \rm nm[/tex] is measured in vacuum, where the speed of light is approximately [tex]3.0\times 10^{8}\; \rm m \cdot s^{-1}[/tex].)

Explanation:

Convert the unit of wavelength to meters:

[tex]\displaystyle \lambda = 525\; \rm nm = 525 \; \rm nm\times \frac{10^{-9}\; \rm m}{1\; \rm nm} = 5.25 \times 10^{-7}\; \rm m[/tex].

Assume that the wavelength [tex]525\; \rm nm[/tex] is measured in vacuum, where the speed of light is approximately [tex]2.99792\times 10^{8}\; \rm m \cdot s^{-1}[/tex]. Calculate the frequency of this light from its wavelength:

[tex]\displaystyle f = \frac{c}{\lambda} \approx \frac{2.99792\times 10^{8}\; \rm m \cdot s^{-1}}{5.25 \times 10^{-7}\; \rm m} \approx 5.71429\times 10^{14}\; \rm s^{-1}[/tex].

The Planck's Constant can help find the energy of a photon given its frequency. Look up this constant to more than three significant figures:

[tex]h \approx 6.62607\times 10^{-34}\; \rm J \cdot s^{-1}[/tex].

Calculate the energy of one such photon:

[tex]\begin{aligned} E &= h \cdot f\\ &\approx 6.62607\times 10^{-34}\; \rm J \cdot s^{-1} \times 5.71023\times 10^{14}\; \rm s \\ &\approx 3.78370\times 10^{-19}\; \rm J \end{aligned}[/tex].

Calculate the number of these photons that [tex]100\; \rm J[/tex] of energy can produce under the assumption of [tex]100\%[/tex] conversion:

[tex]\displaystyle \frac{100\; \rm J}{3.78370\times 10^{-19}\; \rm J} \approx 2.64\times 10^{20}[/tex].

(Rounded to three significant figures.)

Answer:

Explanation:

The average speed of a body can be found by using the formula

[tex]Average \: \: speed = \frac{distance}{time} [/tex]

To find the average speed in km/h first convert the distance from m to km and the seconds from s to hr.

For the distance

2000 m

1000 m = 1 km

2000 m = 2000/1000 = 2 km

For the seconds

21.9 s

3600 s = 1 hr

21.9 s = 21.9/3600 = 0.006 hrs

Substitute the values into the above formula and solve for the Average speed

That's

[tex]Average \: \: speed = \frac{2}{0.006} [/tex]

We have the final answer as

Average speed = 333.3 km/hr

Hope this helps you

Answer:

11

Explanation:

so that is 20\100× 55 that gives you 11

thanks so please follow me

Answer:

4.

Explanation:

Hello,

In this case, for the calculation of the degree of unsaturation, we apply the following formula:

[tex]Degree\ of \ insaturation=C-\frac{H}{2}[/tex]

Thus, since we have eight carbon atoms and twelve hydrogen atoms, it turns out:

[tex]Degree\ of \ insaturation=8-\frac{12}{2}=8-6=4[/tex]

It means that four substituents are missing in order saturate the molecule.

Regards.

Answer:

Average weekly rate of mowing lawns = 13 lawns (Approx)

Explanation:

Given:

Total lawns mowed = 229

Total number of period = 18 week

Find:

Average weekly rate of mowing lawns

Computation:

Average weekly rate of mowing lawns = Total lawns mowed / Total number of period

Average weekly rate of mowing lawns = 229 / 18

Average weekly rate of mowing lawns = 12.72

Average weekly rate of mowing lawns = 13 lawns (Approx)

Answer:

1.12x10⁷ mi / min

Explanation:

Speed is a magnitude defined as the distance an object travels per unit of time.

Speed light is 3.00x10⁸ m/s. To convert this to miles per minute we need to convert the meters to miles and the seconds to minutes:

3.00x10⁸ m/s * (1mi / 1609.344m) = 186411.4 mi/s

186411.4 mi/s * (60s / 1min) =

Answer:

Plz make me brainliest

Explanation:

The neurotransmitters released into the cleft diffuse through it to reach the post-synaptic neuron. Neurotransmitters remain in cleft for only some time. They are either taken up by the presynaptic neuron or are broken down by the enzymes present in the synaptic cleft. The post-synaptic neuron contains several receptors on its plasma membrane

Answer:

474 grams of chlorine gas are present in a 150 liter cylinder of chlorine held at a pressure of 1.00 atm and 0 °C

Explanation:

An ideal gas is a theoretical gas that is considered to be composed of randomly moving point particles that do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.

The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:  

P*V = n*R*T

where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas.

In this case:

Replacing:

1.00 atm* 150 L= n*0.08206 [tex]\frac{atm*L}{mol*K}[/tex] *273 K

Solving:

[tex]n=\frac{1.00 atm* 150 L}{0.08206 \frac{atm*L}{mol*K}*273 K}[/tex]

n= 6.69 moles

Being Cl= 35.45 g/mole, the molar mass of chlorine gas is:

Cl₂=2*35.45 g/mole= 70.9 g/mole

So if 1 mole has 70.9 grams, 6.69 moles of the gas, how much mass does it have?

[tex]mass=\frac{6.69 moles*70.9 grams}{1 mole}[/tex]

mass= 474.321 grams ≅ 474 grams

474 grams of chlorine gas are present in a 150 liter cylinder of chlorine held at a pressure of 1.00 atm and 0 °C

though alchemists were often superstitious, they left a rich legacy of modern chemists. what was their main contribution-

Explanation:

they were the first to preform experiments.

Answer:

0.25 M

Explanation:

Data obtained from the question include:

Molar mass of NaCl = 58.55 g/mol

Mass of NaCl = 0.800 g

Volume = 54.6 mL

Next, we shall determine the number of mole in 0.800 g of NaCl. This can be obtained as follow:

Molar mass of NaCl = 58.55 g/mol

Mass of NaCl = 0.800 g

Mole of NaCl =?

Mole = mass /Molar mass

Mole of NaCl = 0.8/58.55

Mole of NaCl = 0.0137 mole

Next, we shall convert 54.6 mL to litres (L). This can be obtained as follow:

1000 mL = 1 L

Therefore,

54.6 mL = 54.6 /1000

54.6 mL = 0.0546 L

Finally, we shall determine the molarity of the solution as follow:

Mole of NaCl = 0.0137 mole

Volume = 0.0546 L

Molarity =?

Mol= mole /Volume

Molarity = 0.0137/0.0546

Molarity = 0.25M

Therefore, the molarity of the solution is 0.25 M

D. Make observations

The first thing you do is write a hypothesis then you were designed your procedure, after you make the procedure you would do the procedure, after you do the procedure you would confirm the results, then at the end you would make observations to see that everything is correct.

Answer:

Explanation:

wt. of the lead = wt. of ( flask + lead) - wt.of the empty flask

                      350.52- 245.61= 104.91 grams of lead

density = mass/volume

11.43= 104.91/V

V =  9.178 ml

Answer:

Explanation:

A mole is the amount of substance that contains as many elementary entities as there are carbon atoms in 12 grams of carbon -12 isotopes i.e. it is the amount of a substance that posses the same number of particles as the number of atoms in exactly 12g of carbon is 12.

The number of atoms in a mole is known to be the Avogadro Number which is equal to 6.02 × 10²³. Thus, a mole of any substance is that amount of the substance which contains 6.02 × 10²³ particles of that substance. The definition of the mole is also given by the relationship:

[tex]\mathtt {moles = \dfrac{ mass \ in \ grams}{ relative \ molecular \ mass}}[/tex]

Answer:

THE EMPIRICAL FORMULA OF THE COMPOUND IS Ir Se2

Explanation:

Iridium = 16.7 g

Selenium = 10.3 g

Total mass = 16.7 + 10.3 = 27 g

To calculate the empirical formula, we first calculate the percentage com[position of the individual elements.

Percentage composition of iridium = 16.7 / 27 * 100 = 61.85 %

Percentage composition of selenium = 10.3 / 27 * 100 = 38.15 %

Next is to divide the percentage composition of each element by their respective molecular masses

Molecular mass of iridium = 192 g/mol

Molecular mass of selenium = 79g/mol

Iridium = 61.85 / 192 =  0.3221

Selenium = 38.15 / 79 = 0.4829

Next is to divide the values by the smaller of the two values

Iridium = 0.3221 / 0.3221 = 1

Selenium = 0.4829 / 0.3221 = 1.5

Next is to round up the values to a whole number

Iridium = 1

Selenium = 2

The empirical formula therefore is Ir Se2

Answer:

Explanation:

Start by sifting the marbles out bc they are bigger they will sit in a big sifter

Than with a magnet roll it in what’s left this will pick up all the iron pieces

Than Fill with water and stir this should resolve the sugar which after you sift out the sand you can heat and scrape off beaker and than for a very short time heat up the sand to dry it and not have extra weight from the water

!!!sand only for a few seconds or else it will fly everywhere and if it gets in eye it will sting badly

Answer:

Paraffin > Heptadecane > Hexane > 2,2-dimethylbutane > Propane

Explanation:

It must first be establish that all the molecules listed in the question are alkanes. For alkanes, the intermolecular forces between the molecules of alkanes increases with increasing molecular weight. This is as a result of increase in the surface area of the molecule. Increase in surface area implies a greater degree of dispersion forces.

This is the reason why high boiling points are observed for high molecular weight alkanes.

Answer:

CaCO3,which is Calcium Carbonate. It’s equivalent mass is 50 g. Explanation:-. Mass of CaCO3=Mass of 1 atom of Calcium (Ca)+Mass of 1 atom of Carbon (C)+Mass of 3 atoms of Oxygen (O). Mass of 1 atom of Calcium=1×40g=40g. Mass of 1 atom of Carbon=1×12g=12g. Mass of 3 atoms of Oxygen=3×16g=48g.

Explanation:  Hope this helps :)

Answer:

The liquid state has a definite volume and a definite shape.

Answer:

1×10⁸ Hz.

Explanation:

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

Wavelength (λ) = 3 m

Frequency (f) =?

The wavelength of a wave and it's frequency are related by the following equation:

Velocity (v) = wavelength (λ) × frequency (f)

v = λf

With the above equation, we can obtain the frequency of the light wave as follow:

Wavelength (λ) = 3 m

Velocity (v) of light = 3×10⁸ m/s

Frequency (f) =?

v = λf

3×10⁸ = 3 × f

Divide both side by 3

f = 3×10⁸ / 3

f = 1×10⁸ Hz

Therefore, the frequency of the light wave is 1×10⁸ Hz

Answer:

Explanation:

The density of a substance can be found by using the formula

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

To find the density in g/mL , we must first convert the volume from L to mL

From the question

mass = 440 g

1 L = 1000 mL

0.27 L = 0.27 × 1000 = 270 mL

volume = 270 mL

Substitute the values into the above formula and solve for the Density

That's

[tex]Density = \frac{440}{270} [/tex]

= 1.629629...

We have the final answer as

Hope this helps you

Answer:

heterogeneous

Explanation:

Answer : The correct IUPAC name for the compound is, 2,2,4,5-tetramethyl-3-ethylhexane.

Explanation :

The basic rules for naming of hydrocarbons are :

First select the longest possible carbon chain.

The longest possible carbon chain should include the carbons of double or triple bonds.

The naming of alkane is done by adding the suffix -ane, alkene by adding the suffix -ene, alkyne by adding the suffix -yne.

If two or more similar alkyl groups are present in a compound, the prefixes di-, tri-, tetra- and so on are used to specify the number of times of the alkyl groups in the chain.

In the give compound, the longest possible carbon chain has 6 carbon atoms. So, the prefix used will be 'hex-' and also the carbon has single bond between them, so it is an alkane. Four methyl group is present at 2,2,4,5 position of carbon chain and one ethyl group is present at 3 position.

Hence, the correct IUPAC name for the compound is, 2,2,4,5-tetramethyl-3-ethylhexane.

Tetramethyl-2,2,4,5-ethylhexane is the proper IUPAC name for the substance.

Basic guidelines for hydrocarbon naming are as follows:

Choose the longest carbon chain you can.

The carbons of double or triple bonds should be included in the longest carbon chain possible.

The suffixes -ane, -ene, and -yne are used in the naming of alkane, alkene, and alkyne, respectively.

If a compound has two or more identical alkyl groups, the prefixes di-, tri-, tetra-, and so on are used to indicate how many times the alkyl groups are present in the chain.

The longest feasible carbon chain in the given chemical contains 6 carbon atoms. Since there is only one bond between the carbon atoms, the prefix will be "hex-," and an alkane is what is being described. On the carbon chain, there are four methyl groups at positions 2, 2, 4, and 5, and one ethyl group at position 3. Consequently, 2,2,4,5-tetramethyl-3-ethylhexane is the right IUPAC designation for the substance.

To know more about IUPAC, here:

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Answer:

a. 0.154 moles = 2.78x10²³ ions

b. 2.18x10⁻⁴ moles = 6.56x10²⁰ ions

c. 1.77x10²² ions = 0.0147 moles

Explanation:

The multiplication of volume of solution in liters times molarity gives the moles of solute.

a. Moles MgCl₂:

88mL = 0.088L * (1.75mol / L) = 0.154 moles MgCl₂

Uaing Avogadro's number:

0.154mol  *(6.022x10²³ molecules / 1 mol) = 9.27x10²² molecules.

As 1 molecule of MgCl₂ contains 3 ions:

Ions = 2.78x10²³

b. Moles Al₂(SO₄)₃:

Aluminium sulfate has a molar mass of 324.15g/mol:

0.321L * (0.22g Al₂(SO₄)₃ / L) * (1mol / 324.15g) = 2.18x10⁻⁴ moles.

1 molecule contains 5 ions:

2.18x10⁻⁴ moles  *(6.022x10²³ molecules / 1 mol) * 5 = 6.56x10²⁰ ions.

c. 8.83x10²¹ formula units of CsNO₃ = Number of molecules. Ions are:

8.83x10²¹ * 2 = 1.77x10²² ions

And moles are:

8.83x10²¹ Formula units * (1mol /  6.022x10²³) = 0.0147 moles

a. The number of moles and number of ions should be 0.154 moles and 2.78x10²³ ions

b. The number of moles and number of ions should be 2.18x10⁻⁴ moles and 6.56x10²⁰ ions

c.  The number of moles and number of ions should be 1.77x10²² ions and  0.0147 moles

a. Moles MgCl₂:

Here,

88mL = 0.088L * (1.75mol / L) = 0.154 moles MgCl₂

Now here we used Avogadro's number:

So,

0.154mol  *(6.022x10²³ molecules / 1 mol) = 9.27x10²² molecules.

Since 1 molecule of MgCl₂ contains 3 ions:

So,

Ions = 2.78x10²³

b. Moles Al₂(SO₄)₃:

Since Aluminum sulfate has a molar mass of 324.15g/mol:

So,

0.321L * (0.22g Al₂(SO₄)₃ / L) * (1mol / 324.15g) = 2.18x10⁻⁴ moles.

Now

1 molecule contains 5 ions:

So,

2.18x10⁻⁴ moles  *(6.022x10²³ molecules / 1 mol) * 5 = 6.56x10²⁰ ions.

c. Since

8.83x10²¹ formula units of CsNO₃ = Number of molecules. Ions are:

So,

8.83x10²¹ * 2 = 1.77x10²² ions

And moles are:

8.83x10²¹ Formula units * (1mol /  6.022x10²³) = 0.0147 moles

learn more about moles here: https://brainly.com/question/24817060

Answer:

Dosage of acetaminophen = 15.9 cg acetaminophen

Explanation:

Given:

1 teaspoon = 10.6 cg acetaminophen

Dosage to 34 lbs child = 34 lbs

Given dose = 1.5 teaspoon

Find:

Dosage of acetaminophen

Computation:

⇒ Dosage of acetaminophen = 1.5 teaspoon × [10.6 cg acetaminophen]

Dosage of acetaminophen = 15.9 cg acetaminophen

Answer:

an object that is at rest will stay at rest inless a force acts upon it.

An oject that is in motion will not change its velocity unless a force acts upon it.

Answer:

First law

In an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.[2][3]

Second law

In an inertial frame of reference, the vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object: F = ma. (It is assumed here that the mass m is constant – see below.)

Third law

When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

Answer:

Explanation:

An amino acid like lysine has both the acidic and basic group . They are amphoteric in nature ie they can react with both acid and base . In acidic or basic medium they carry charge of either positive or negative nature .

Lysine is also an amino acid . It has both acidic and basic group . The pka value of its basic side chain is 10.5 . Hence at pH more than it it is neutral or have no charge but at pH value less than 10.5 , it acquires H⁺ ion and becomes positively charged

Hence at pH value of 9.5 which is less than 10.5 , it will be positively charged . It will have net charge of + 1 .

----    NH₂  + H⁺ =     ------ NH₃⁺

Answer:

C. BH_3

Explanation:

The VSEPR is known as the valence shell electron pair repulsion theory. The VSEPR theory determines the total number of electron pairs (TEP) surrounding the central atom of a species. The TEP consists of the bond pairs (BP) and lone pairs (LP). In this model, all the electron pairs (like charges) will orient themselves in such a way as to minimize the electrostatic repulsion between them. These repulsions determine the geometry of the covalent bonds around the central atom.

In the options given, all the molecules have identical geometry except BH_3. This is as a result of the absence of a lone pair on the BH_3 compound.

Answer:

A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements.A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements.

Explanation:

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