Please help me with this chem question

Answer:

0.0457 M

Explanation:

The reaction that takes place is:

First we calculate how many moles of acid reacted, using the HBr solution's concentration and volume:

Now we convert HBr moles to Ca(OH)₂ moles, using the stoichiometric ratio:

Finally we calculate the molarity of the Ca(OH)₂ solution, using the given volume and calculated moles:

All solutions are mixtures of two or more substances, but unless the mixture has a homogeneous distribution of solutes in the solvent, then the mixture is not a solution. Therefore, all mixtures are not solutions.

Answer:

212 degrees Fahrenheit

Explanation:

When liquid water reaches a low enough temperature, it freezes and becomes a solid—ice. When solid water is exposed to enough heat, it will melt and return to a liquid. As that liquid water is further heated, it evaporates and becomes a gas—water vapor.

Answer:

A) 0.801

Explanation:

The reaction that takes place is:

First we calculate the H₂SO₄ moles that reacted:

Now we convert H₂SO₄ moles to NaOH moles:

Finally we calculate the molarity of the NaOH solution:

So the answer is option A.

The molarity of the NaOH solution used in the neutralization reaction has been 0.801 [tex]\rm \times\;10^-^3[/tex] M. Thus, option A is correct.

The neutralization reaction has resulted in the formation of the salt and water on reacting an acid with a base. In the neutralization reaction, the strength of acid and base can be given as:

[tex]\rm 2\;NaOH\;+\;H_2SO_4\;\rightarrow\;Na_2SO_4\;+\;H_2O[/tex]

For the neutralization of 1 mole of sulfuric acid, 2 moles of NaOH has been required.

The moles of sulfuric acid can be given as:

Moles = Molarity × Volume

Given, the molarity of acid ([tex]\rm H_2SO_4[/tex]) = 0.355 M

Volume of acid = 28.2 ml = 0.0282 L

Volume of base (NaOH) = 25 ml = 0.025 L

Moles of [tex]\rm H_2SO_4[/tex] = 0.355 × 0.0282 mol

Moles of [tex]\rm H_2SO_4[/tex] = 10.011  mol.

Since, 1 mole [tex]\rm H_2SO_4[/tex] = 2 moles NaOH

10.011 moles [tex]\rm H_2SO_4[/tex] = 10.011 × 2 moles NaOH

10.011 moles [tex]\rm H_2SO_4[/tex] = 20.022 moles NaOH.

The neutralization of 0.355 M [tex]\rm H_2SO_4[/tex] requires 20.022 moles NaOH. The strength of the NaOH solution will be:

Molarity = [tex]\rm \dfrac{Moles}{Volume\;(L)}[/tex]

Molarity of NaOH = [tex]\rm \dfrac{20.022}{0.025}[/tex]

Molarity of NaOH = 0.801 [tex]\rm \times\;10^-^3[/tex] M.

The molarity of the NaOH solution used in the neutralization reaction has been 0.801 [tex]\rm \times\;10^-^3[/tex] M. Thus, option A is correct.

For more information about the neutralization reaction, refer to the link:

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Answer:

A scientific method is the one which is independent of the person taking the measurements. Hence, a method which includes a scientific instrument/experiment, systematic observation, measurement, testing etc and is independent of personal feelings or opinions is known as a scientific method.

The measurement of temperature, testing of the material of surface, and moisture content in the atmosphere are testable questions and part of scientific method to find the reasons of different shapes of dewdrops. whether the different shapes are formed due to change in temperature, surface or moisture content in the atmosphere or not? The result of this measurement would not depend on the scientist doing the experiment. Scientific instruments would be used which would give the same reading. But the result of the observation of most unusual shape and pleasing shape of drop is purely dependent on one observer. It cannot be generalized reason

Explanation:

Answer:

brainliest pls pls pls

Explanation:

Answer:

87.5 %

Explanation:

Step 1: Given data

Step 2: Calculate the percent yield

When working with chemical reactions, we can determine the efficience in obtaining a product measuring the percent yield. The theoretical yield is the maximum amount of product that we could obtain according to the stoichiometry, whereas the real yield is the amount of product that we actually obtain when we carry out the process. We can calculate the percent yield usign the following expression.

%yield = real yield / theoretical yield × 100%

%yield = 105 kg / 120 kg × 100%

%yield = 87.5 %

One major characteristic they have in common is they are metals.

Answer:

138mL are required to make the solution

Explanation:

A solution of 0.270M contains 0.270 moles of solute (NaCl in this case), per liter of solution.

To solve this problem we need to determine the moles of NaCl in 2.18g. With these moles and molarity we can find the volume required to prepare the solution:

Moles NaCl -Molar mass: 58.44g/mol-:

2.18g * (1mol / 58.44g) = 0.0373moles NaCl

Volume of solution:

0.0373moles NaCl * (1L / 0.270moles) = 0.138L

Answer:

255.732 g/mol

Explanation:

Molar mass of Ga(NO3)3 = 255.7322 g/mol. This compound is also known as Gallium(III) Nitrate.

Answer:

Balanced Chemical Equation

CH4 + 4Cl2 → CCl4 + 4HCl

Explanation:

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The density of metal = 4.5 g/ml, and the metal = Titanium

Density is a quantity derived from the mass and volume  

Density is the ratio of mass per unit volume  

Density formula:  

[tex]\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}[/tex]

ρ = density  

m = mass  

v = volume  

mass of metal=27 g

volume = 6 ml

The density :

[tex]\tt \rho=\dfrac{27}{6}\\\\\rho=4.5~g/ml[/tex]

The metal with a density of 4.5 g/ml is Titanium

Answer:

0.0196

Explanation:

The Total volume of the solution = Volume of [tex](KBrO_3 + HCl + KI +Na_2S_2O_3 + Starch + H_2O)[/tex]

= 10 mL + 10 mL + 10 mL+ 10 mL + 1 mL + 10 mL

= 51 mL

The concentration of  [tex][H^+] = \dfrac{ mL \ used \times 0.1 \ M}{total \ volume}[/tex]

[tex]= \dfrac{10 \ mL \times 0.1 M}{51 \ mL}[/tex]

= 0.0196

Answer:

The ability of an atom to accept an electron.

Explanation:

Electron affinity is measured by observing the energy change of a substance when an electron is added to it in its neutral gas form. For example, elements that are on the far right of the periodic table (excluding noble gases) are more likely to accept electrons rather than give them up. This is why Fluorine has the highest electron affinity of all atoms on the periodic table.

Answer: Cul2 + Br2 ->

Explanation:

Answer:

i believe the answer is a

Explanation:

Answer:

Beta particles

Explanation:

A beta emission is said to occur when a neutron is converted into a proton. When a beta emission takes place, the daughter nucleus increases it's atomic number by 1. A neutrino is also produced.

Since the mass number remain the same but the daughter nucleus has it's atomic number increased by 1, then the particle is a beta particle.

Answer: D

Explanation: because the earth is slanted and at the north and south pole do not get that much sunlight so that makes it colder than most places on earth

Answer:

Average atomic mass  = 57.79 amu

Percent contribution of Ni-60 = 26.45%

Percent contribution of Ni-5 =  73.55%

Explanation:

Given data:

Number of atoms of Ni-60 = 32

Number of atoms of Ni-57 = 89

Percent distribution of both isotopes = ?

Average atomic mass of sample = ?

Solution:

Percent contribution:

Total number of atoms = Ni-60 + Ni-57

Total number of atoms = 32 +89 = 121

Percent contribution of Ni-60 = 32/121×100

                                             =   26.45%

Percent contribution of Ni-57 = 89/121×100

                                             =  73.55%

Average atomic mass:

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass  = (26.45×60)+(73.55×57) /100

Average atomic mass =  1587 + 4192.35 / 100

Average atomic mass  = 5779.35 / 100

Average atomic mass  = 57.79 amu.

Answer:

D 4,3,2

Explanation:

4 Co + 3 O2 ----> 2 Co2O3

The frequency of photon=6.03 x 10³³ /s

Radiation energy is absorbed by photons

The energy in one photon can be formulated as

[tex]\large{\boxed{\bold{E\:=\:h\:.\:f}}}[/tex]

Where

h = Planck's constant (6,626.10⁻³⁴ Js)

f = Frequency of electromagnetic waves

Energy of photon = 4 J

So the frequency :

[tex]\tt f=\dfrac{E}{h}\\\\f=\dfrac{4}{6.626.10^{-34}}\\\\f=6.03.10^{33}/s[/tex]

Answer:

Thermal

Explanation:

When something heats up its atoms become further apart making it melt when something heats up or gets heat or loses heat that's thermal energy

Answer:

153.56g

Explanation:

Number of moles = mass/molar mass

To get the number of moles of the molecule, we divide the number of molecules contained by Avagadro's number, which is 6.02 × 10^23 molecules.

moles = 4.12 × 10^24 ÷ 6.02 × 10^23

number of moles = 0.684 × 10^(24-23)

number of moles = 0.684 × 10^(1)

number of moles = 6.84mol

If the molar mass of the molecule is 22.45 g/mol, the mass of the molecule can be calculated thus:

mass = moles × molar mass (MM)

mass = 6.84 × 22.45

mass = 153.558

mass = 153.56g

Answer:

D. Upper right

Explanation:

The position the student should look for such element is in the upper right corner before the noble gases.

Specifically, the group of halogens will react vigorously with lithium.

Answer:

D. Upper right

Explanation:

I had the exact same question

Answer:

that one or more new substances are produced. Temperature Changes Chemical reactions can release energy or absorb energy.

Explanation:       .

Answer: The half life of the sample of silver-112 is 3.303 hours.

Explanation:

All radioactive decay processes undergoes first order reaction.

To calculate the rate constant for first order reaction, we use the integrated rate law equation for first order, which is:

[tex]k=\frac{2.303}{t}\log \frac{[A_o]}{[A]}[/tex]

where,

k = rate constant = ?

t = time taken = 1.52 hrs

[tex][A_o][/tex] = Initial concentration of reactant = 100 g

[A] = Concentration of reactant left after time 't' = [100 - 27.3] = 72.7 g

Putting values in above equation, we get:

[tex]k=\frac{2.303}{1.52hrs}\log \frac{100}{72.7}\\\\k= 0.2098hr^{-1}[/tex]

To calculate the half life period of first order reaction, we use the equation:

[tex]t_{1/2}=\frac{0.693}{k}[/tex]

where,

[tex]t_{1/2}[/tex] = half life period of first order reaction = ?

k = rate constant = [tex]0.2098hr^{-1}[/tex]

Putting values in above equation, we get:

[tex]t_{1/2}=\frac{0.693}{0.2098hr^{-1}}\\\\t_{1/2}=3.303hrs[/tex]

Hence, the half life of the sample of silver-112 is 3.303 hours.

Answer:

5.61 e⁻³

Explanation:

Given that:

The barrier length = 0.681 nm = 6.81 × 10⁻¹⁰

The difference between the height of the barrier & the energy of the electron is;

[tex]V - E = 0.554 \ eV (1.6 \times 10^{-19} )[/tex]

= 8.864 × 10⁻²⁰ V

where;

m = 9.1 × 10⁻³¹ kg

The probability[tex]P = e^{-2 \ kd}[/tex]

[tex]k = 2 \pi \sqrt{\dfrac{2m (V-E)}{h^2} }[/tex]

[tex]k = 2 \pi \times \dfrac{\sqrt{2 \times 9.1 \times 10^{-31} \times 8.864 \times 10^{-20}}}{6.63 \times 10^{-34}}[/tex]

k = 3.806 × 10⁹

[tex]P = e^{-2 \ kd}[/tex]

[tex]P = e^{2 \times 3.806 \times 10^9 \times 6.81 \times 10^{-10}}[/tex]

P = 0.005606

P = 5.61 × 10⁻³

P = 5.61 e⁻³

The observations of the tree's characteristics would be useful in determining its identity with a dichotomous key is its leaves are long and narrow. The correct option is B.

Observation is a process of recognizing and recording an event or fact that frequently involves measuring it with tools. Recognizing and recording an event, or fact frequently involves measuring with tools. Field notes are written observations made while participating in field observations or immediately afterward.

They are crucial for understanding phenomena that have been seen in the field. Field notes frequently take the form of scratch notes, diaries, and notebooks. In the scientific field, observation is a crucial step.

Therefore, the correct option is B. Its leaves are long and narrow.

To learn more about observation, refer to the link:

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Answer:

3.69 g

Explanation:

Given that:

The mass m = 325 g

The change in temperature ΔT = ( 1540 - 165)° C

= 1375 ° C

Heat capacity [tex]c_p[/tex] = 0.490 J/g°C

The amount of heat required:

q = mcΔT

q =  325 × 0.490 × 1375

q = 218968.75 J

q = 218.97 kJ

The equation for the reaction is expressed as:

[tex]C_2H_{2(g)} + 5O_{2(g)} \to 2CO_{2(g)} + H_2O_{(g)} \ \ \ \ \ \Delta H^o_{reaction} = -1544 \ kJ[/tex]

Then,

1 mole of the ethyne is equal to 26 g of ethyne required for 1544 kJ heat.

Thus, for 218.97 kJ, the amount of ethyne gas required will be:

[tex]= \dfrac{26 \ g}{1544 \ kJ} \times 218.97 \ kJ[/tex]

= 3.69 g

Answer:uclear Force that holds together the nucleus of an atom. electromagnetic force. ... They are unstable because the Strong Force that would hold them together if the protons and neutrons were closer is weakened because the protons and neutrons get too far apart.

Explanation:

Nuetrons, Electrons, and Protons.