If you have a 60 Watt light bulb and a 75 Watt light bulb that are going to stay lit for 2.5 days, how many photons with a wavelength of 650 nm would it take to get the job done?

Answer:

true

Explanation:

PV=nRT

The ideal gas law states that PV = NkT, where P is the absolute pressure of a gas, V is the volume it occupies, N is the number of atoms and molecules in the gas, and T is its absolute temperature. The constant R is called the Boltzmann constant

Answer:

x = -9, 0 = -1, x \ne 0

Explanation:

[-54/x = 6  0x = 9]

Isolate x for - 54/x = 6 : x = -9

-54/x = 6

Multiply both sides by x

-54/x = 6x

Simplify - 54/x x :  -54

-54x x = 6x

Multiply fractions: a . b/c = a . b/c

= -54x/x

Cancel the common factor: x

= -54

- 54 = 6x

Switch sides

6x = -54

Divide both sides by 6

6x/6 = -54/6

Simplify

6x/6 = -54/6

Simplify 6x/6:  -9

6x/6

Divide the numbers: 6/6 = 1

= x

Simplify

-54/6

Apply the fraction rule: -a/b = -a/b

= -54/6

Divide the numbers: 54/6 = 9

= -9

x = -9

Verify solutions

Find underfined (singularity) point: x = 0

Take the denominator (s) of - 54/x and compare to zero

x = 0

Combine undefined points with solutions:

x = -9

Substitute x = -9

[ o(-9) = 9]

Simplify

0(-9) = 9

Simplify

0(-9): -90

Remove parentheses: (-a) = -a

= -0 . 9

-90 = 9

[-90 = 9]

Isolate o for -90 = 9 : o = -1

-90 = 9

Divide both sides by -9

-90/-9 = 9/-9

Simplify

0 = -1

The solutions to the system of equations are:

x = -9, 0 = -1, x \ne 0

The question is: What is the boiling point of an aqueous solution of urea at 20% m / m (20g of solute for every 80g of solvent), if the molar mass of urea is 60 g / mol. (Kb = 0.52 ° C / m)

Answer: The boiling point of given aqueous solution of urea is [tex]2.145^{o}C[/tex].

Explanation:

Given: Mass of solute = 20 g

Mass of solvent = 80 g (1 g = 0.001 kg) = 0.08 kg

[tex]K_{b} = 0.52^{o}C/m[/tex]

Molar mass of urea = 60 g

Molality is the number of moles of solute present in a kg of solvent.

Moles is the mass of a substance divided by its molar mass. So, moles of urea is calculated as follows.

[tex]Moles = \frac{mass}{molar mass}\\= \frac{20 g}{60 g/mol}\\= 0.33 mol[/tex]

Now, molality of given solution is as follows.

[tex]Molality = \frac{moles}{mass(in kg)}\\= \frac{0.33 mol}{0.08 kg}\\= 4.125 m[/tex]

Formula used to calculate the boiling point is as follows.

[tex]\Delta T_{b} = K_{b}m\\= 0.52^{o}C/m \times 4.125 m\\= 2.145^{o}C[/tex]

Thus, we can conclude the the boiling point of given aqueous solution of urea is [tex]2.145^{o}C[/tex].

Answer:

2(CaSO4)*H2O

Explanation:

To solve this question we need to find the moles water, H2O, of calcium sulfate, CaSO4 as follows:

The molar mass of the anhydrous CaSO4 are 136.14g/mol and the molar mass of the hemihydrate is 145.15g/mol. The differences in molar mass represents the additional mass that water is producing:

145.15g/mol - 136.14g/mol = 9.01g/mol

A 1 mole of water weighs 18.015g/mol, the additional mass of water is due the addition of 1/2 moles of H2O. That means we have 1 mole of CaSO4 per 1/2 mole of H2O. That is the same:

2(CaSO4)*H2O

And this is the formula that gives the correct ratio for the hemihydrate.

Explanation:

Solution is a homogenous mixture of two or more substances in relative amounts that can be varied continuously up to what is called the limit of solubility.

A mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance

A suspension is a heterogeneous mixture of a finely distributed solid in a liquid. The solid is not dissolved in the liquid, as is the case with a mixture of salt and water.

Answer:

iii) Figure 2 needs to have one X in the intersection, and one O in the intersection. This is because hydrogen requires 2 electrons in it’s outer shell to become stable. By sharing, both hydrogen atoms can become stable.

c) (i) Universal indicator.

i’m not 100% sure, however i’m quite certain :)

we use the ideal has law when a bad changes false

Answer:

6

Note:

Please check Rasputin020's answer instead of this, It's more detailed.

Answer:

chemical wsed in hot packs do not produce fire, so what makes the hot packs feel hot? Because it is a exothermic reaction it has chemicals that bunch up together.

The name of the molecule shown is Ethanol.

Ethanol is a alcoholic substance that is formed from fermentation of glucose in the presence of yeast or microorganisms.

It has a chemical group that have methyl group, hydroxyl group OH which is bonded to carbon atom.

Therefore, The name of the molecule shown is Ethanol.

Learn more about ethanol below.

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El catión divalente descrito en la pregunta es [tex]Sn^{2+}[/tex]. Divalente significa que ha perdido dos electrones.

La distribución electrónica de [tex]Sn^{2+}[/tex] es;

  1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10

El número másico de estaño es 118 y [tex]Sn^{2+}[/tex] tiene 50 protones.

Por lo tanto, el número de masa de Sn =[tex]118 - 50 = 68 neutrones[/tex]

El número de electrones es 49 y el número de protones es 50 en [tex]Sn^{2+}[/tex]por tanto;

El número de electrones + protones = 99

El último electrón está en el orbital, 5s2, por lo que sus posibles números cuánticos son;

n = 5, l = 0, m = 0, s = ±1/2

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Answer:

The oxidation state of N in the KNO3 is +5

Explanation:

Oxidation rules:

1. Oxygen is -2, unless in peroxides.

2. Group 1 metals = +1

3. Group 2 metals = +2

4. If the molecule is neutral, all of the oxidation numbers have to add up to zero.

5. If the molecule is charged, all of the oxidation numbers have to add up to the charge of the molecule.  

So, the given formula represents the salt compound formula unit of potassium nitrate:  KNO3  

The formula unit is uncharged.

From our rules, we know that,

O = -2

And we can find K on the periodic table, in the first group, thus giving it a +1 charge. Now let's put it all together.

K = +1

N = x

O = -2

Let's take into account the number of atoms of each element we have and make an equation since we know everything has to add up to zero since the molecules are neutral.

+1 +x+3 (-2) = 0 (notice we multiplied 3 by -2 because in the formula we have 3 atoms of oxygen with -2 charge each)

x - 5 = 0

x = 5

Therefore, the oxidation number of N in KNO3 is +5.

Answer:

Hence the correct answer is increase, electronegativity.

Explanation:

Oxoacids have the general formula illustrated, where the number of bonds to the central element E can vary. For the same element E, acid strength will increase as the number of O atoms increases. For the same number of O atoms, acid strength increases as the electronegativity of element E increases.

Answer:

[tex][SO_4^{2-}]=4.4*10^{-9}M[/tex]

Explanation:

From the question we are told that:

[tex]Ksp=1.1*10^{-10}[/tex]

Volume of [tex]SO_4^{2-}=1.O[/tex]

Moles of  [tex]Ba(NO_3)^2 =0.025[/tex]

Generally the equation for Ksp is mathematically given by

[tex]Ksp=[Ba^{2+}][SO_4^{2-}][/tex]

[tex]1.1*10^{-10}=[0.025][SO_4^{2-}][/tex]

Therefore

[tex][SO_4^{2-}]=4.4*10^{-9}M[/tex]

Answer:Nhóm gồm tất cả các kim loại tan trong axit sunfuric đặc nóng nhưng không tan trong axit sunfuric lo

Al, Cu, Au.

Al, Fe, Cr.

Ag, Fe, Pt.

Ag, Cu, Hg.

Explanation:

Answer:

"0.583" is the appropriate answer.

Explanation:

Let,

The initial constant of [tex]N_2O_4[/tex] be "C".

Amount of [tex]N_2O_4[/tex] dissociated into [tex]NO_2[/tex] be "x".

now,

                                     [tex]N_2O_4 \rightleftharpoons 2NO_2[/tex]

Initial constant               C            -

Equilibrium constant     C          2x

The Kc is given as:

⇒ [tex]K_c = \frac{[NO_2]^2}{[N_2O_4]}[/tex]

         [tex]=\frac{(2x)^2}{C-x}[/tex]

[tex]0.593=\frac{4x^2}{0.88-x}[/tex]

  [tex]4x^2=0.593(0.88-x)[/tex]

  [tex]4x^2=0.512-0.593\ x[/tex]

     [tex]x=0.291[/tex]

hence,

The constant of [tex]NO_2[/tex] will be:

= [tex]2x[/tex]

= [tex]0.583[/tex]

Answer:

elementos original

set onde

Answer:

Explanation:

Answer:

On a Plateu on a heating curve phase changes are occuring

Explanation:

The first Phase is melting during which the temrature stays the same while water melts.Other phase changes are freezing sublimation Vaourization condensation and deposition

Answer:

0.3549

Explanation:

the percentage yield is the percentage of the product formed based on the theoretical yield.in this question the percentage yield and theoretical yield have been given all that's left is the actual yield.so you use the formula

percentage yield=theoretical yield/actual yield×100

83.4=0.296/ay×100

83.4ay/83.4=100×0.296/83.4

ay=0.3549

I hope this helps

Answer:

CHEMICAL REACTION : A process in which new substances with new properties are formed from one or more substances.

Examples of chemical reactions : Digestion of food, respiration, rusting of iron, burning of magnesium ribbon, formation of curd etc.

Answer:

Explanation:

Chemical reaction is one or more reactants react with each other to from new products.

Answer:

Like many common group 2 metal carbonates, magnesium carbonate reacts with aqueous acids to release carbon dioxide and water

 MgCO3 + 2 HCl → MgCl2 + CO2 + H2O.

The procedure to obtain pure magnesium chloride from the reaction is as thus

Step 1: Reaction

- Leave the dilute hydrochloric acid in a beaker.

- Add Magnesium carbonate slowly until it is in excess or until no more gas seem to be getting liberated.

Step 2: Filtration

- Filter with filter paper and funnel.

- Filter off the excess magnesium carbonate as magnesium chloride will be in aqueous form (liquid) and will come out with the filtrate. The residue is the excess magnesium carbonate.

Step 3: Crystallization to obtain solid crystals from the filtrate.

- Pour filtrate solution into evaporating dish/basin

- Provide heat using Bunsen burner

- Pour solution into an evaporating basin and heat over a water bath

- Stop heating when crystals start to form

allow water to evaporate until pure crystals remain.

- Dry crystals using absorbent paper or warm oven.

Precautions

- Use personal protective equipment such as gloves, a lab coat and wear eye protection, especially when heating.

- Avoid inhaling unnecessary gases during the whole process.

Answer:

12g

Explanation:

The following equation is given in this question:

2H2 + O2 → 2H2O

According to this balanced chemical equation, 2 moles of hydrogen gas is used to produce 2 moles of water molecule.

Hence, if 12 grams of hydrogen is used, 12 × 2/2 = 24/2

= 12 grams of H2O will be produced.

The equilibrium concentrations for the given reaction at a certain temperature will be 100.

During a reversible chemical process, chemical equilibrium is the state where there would be no net change in the number of reactants as well as products.

The reaction is the process in which by the combination of more than one element new kind of element will be formed.

Given data:

The given reaction is [tex]N_{2} (g) + O_{2} (g)[/tex]  → [tex]2NO(g)[/tex]

The equilibrium constant (K) = [tex][NO]^{2} /[N_{2}][O_{2}][/tex]

Put the value of the given data in the above equation.

K =  [tex]=[0.002 M]^{2} / [0.65M][0.45M]\\=[4*10^{-6} ]/ [0.2950]\\= [4*10^{-6} ] / 2950*10^{-4}\\= 1.35 * 10^{-5}[/tex]

Therefore, the equilibrium constant will be 1.35 × [tex]10^{-5}[/tex]

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Answer:

V = 6.34 L

Explanation:

Given that,

Number of moles of Helium gas, n = 3.25 mol

Temperature, T = 25 °C = 298 K

Pressure, P = 799 mm Hg

We know that,

PV = nRT

Where

R is the gas constant, R = 62.4 L-mm Hg/mol K

So,

[tex]V=\dfrac{nRT}{P}\\\\V=\dfrac{3.25\times 62.4\times 25}{799}\\\\V=6.34\ L[/tex]

So, the volume of the gas is 6.34 L.

Answer:

oxygen

Explanation:

oxygen ions will be oxidised to form oxygen gas at the anode