Suppose you will determine the composition of the unknown substance that was collected at the scene of the crime. You are encouraged to work on this case. You can perform a series of tests on the unknown substance and compare results of the same tests performed on known samples. Follow these steps:



List physical properties you can use as a simple method of identifying substances.

Describe how you can use density to help identify unknown substances.

Explain how forensic chemist can help you identify unknown substances.

How important is comparing tests results of know substances in a lab setting?

Answer:

Taking the animal kingdom as an example, we can see that it is split into two clear groups: Invertebrates - animals without a backbone. Vertebrates - animals with a backbone.

Explanation:

Answer:

A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge is the same for both the reactants and the products. In other words, the mass and the charge are balanced on both sides of the reaction.

Explanation:

Answer:

wheresthepicture.-

Explanation:

Answer:

don't see a picture

Explanation:

Answer:

Its pressure will be 0.54 atm at 100 K.

Explanation:

Gay-Lussac's law indicates that, as long as the volume of the container containing the gas is constant, as the temperature increases, the gas molecules move faster. Then the number of collisions with the walls increases, that is, the pressure increases. That is, the pressure of the gas is directly proportional to its temperature.

Gay-Lussac's law can be expressed mathematically as the quotient between pressure and temperature equal to a constant:

[tex]\frac{P}{T} =k[/tex]

Studying two different states, an initial state 1 and a final state 2, it is satisfied:

[tex]\frac{P1}{T1} =\frac{P2}{T2}[/tex]

In this case:

Replacing:

[tex]\frac{1.75 atm}{323 K} =\frac{P2}{100 K}[/tex]

Solving:

[tex]P2= 100 k*\frac{1.75 atm}{323 K}[/tex]

P2= 0.54 atm

Its pressure will be 0.54 atm at 100 K.

Answer:

0.076 atm

Explanation:

Using the combined gas law formula;

P1V1/T1 = P2V2/T2

Where;

P1 = initial pressure (atm)

P2 = final pressure (atm)

T1 = initial temperature (K)

T2 = final temperature (K)

V1 = initial volume (L)

V2 = final volume (L)

According to the information provided in this question;

P2 = ?

P1 = 0.250 atm

V2 = 496 L

V1 = 300 L

T2 = 200K

T1 = 400K

Using P1V1/T1 = P2V2/T2

0.250 × 300/400 = P2 × 496/200

75/400 = 496 P2/200

0.1875 = 2.48P2

P2 = 0.1875 ÷ 2.48

P2 = 0.076 atm

Answer:

Titanium(IV) Sulfide

Explanation:

Answer:

Distance = 18 meters

Explanation:

Given the following data;

Force = 50 N

Speed = 1.5 m/s

Time = 12 seconds

To find the distance travelled;

Speed can be defined as distance covered per unit time. Speed is a scalar quantity and as such it has magnitude but no direction.

Mathematically, speed is given by the equation;

[tex]Speed = \frac{distance}{time}[/tex]

Making distance the subject of formula, we have;

Distance = speed * time

Substituting into the formula, we have;

Distance = 1.5 * 12

Distance = 18 meters

Additionally, to find the workdone;

Workdone = force * distance

Workdone = 50 * 18

Workdone = 900 Joules

Answer:

The role of consumers in an ecosystem is to obtain energy by feeding on other organisms and sometimes transfer energy to other consumers. Changes that affect consumers can impact other organisms within the ecosystem.

Explanation:

Hope this helped Mark BRAINLIEST!!!!

Consumers are organisms that obtain energy by eating other organisms. Consumers may consume either producers or other consumers. Consumers include animals.

A food chain is a network of links in a food web that begins with producer organisms and ends with an apex predator, detritivore, or decomposer species.

A food chain also demonstrates how organisms are related to one another through the food they consume. Each trophic level is represented by a different level of a food chain.

Producers can produce their own food and energy, but consumers are not the same. Consumers are living things that must hunt, gather, and eat their food.

Thus, Consumers must eat in order to gain energy, or they will perish. Omnivores, carnivores, herbivores, and decomposers are the four types of consumers.

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Answer:

A. weak acid and its conjugate base

Explanation:

A buffer solution can be made with a weak acid and conjugate base or a weak base and conjugate acid.

This may help you:

https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/Buffers/Introduction_to_Buffers

Answer:

Explanation:

Silver nitrate grams to moles

1 grams Silver Nitrate is equal to 0.0058867472248402 mole

Answer:

K = [HI]² / [H₂] [I₂]

Explanation:

To write the expression of equilibrium constant, K, it is important that we know how to obtain the equilibrium constant.

The equilibrium constant, K for a given reaction is simply defined as the ratio of the concentration of the products raised to their coefficient to the concentration of the reactants raised to their coefficient. Thus, the equilibrium constant is written as follow:

K = [Product] / [Reactant]

Now, we shall determine the equilibrium constant for the reaction given in the question above. This can be obtained as illustrated below:

H₂(g) + I₂(g) —> 2HI (g)

K = [HI]² / [H₂] [I₂]

Answer:

well to me it is called natural energy

Explanation:

when Magnesium is reacted with Aluminum oxide, Aluminum being a less reactive metal than magnesium, is replaced by magnesium

Al2O3 + 3Mg - 3MgO + 2Al

hence reaction takes place

Answer:

Explanation:

Determine the balanced chemical equation for the chemical reaction.

Convert all given information into moles (most likely, through the use of molar mass as a conversion factor).

Calculate the mole ratio from the given information.

Answer: Acids have a sour taste. Lemons, vinegar, and sour candies all contain acids. Acids change the color of certain acid-base indicators. Two common indicators are litmus and phenolphthalein. This are som Characteristics of acid.

Answer:

Explanation:

these are the characteristics of an acid.

hope this helps!

Answer:

D. 108 grams of KNO3(Potassium nitrate)

Answer:

CaC2 + 2H20 ⇋Ca(OH)2 + C2H2

Explanation:

CaC2 + A H20 ---> Ca(OH)2 + A C2H2

This is calcium carbide reacting with water to produce calcium hydroxide and ethyne commonly called acetylene.

Let's now balance the equation.

CaC2 + 2H20 ⇋Ca(OH)2 + C2H2

Answer:Base A is the weakest conductor electricity

Explanation:

Dissociation is a factor that affects electrical conductivity. The greater the percentage of dissociation for bases the stronger the conductivity of electricity.

Given that

Base A dissociates 25% in water

Base B dissociates 50%.

Base C dissociates 75%

We can conclude that  Base A is the weakest conductor oelectricity since it has the lowest percentage of dissociation.

Answer:

See Explanation

Explanation:

1) According to the question, the reactivity of a metal is measured by the temperature of the solution after reaction. The higher the temperature of the solution, the greater the reactivity of the metal. Based on this criterion, the metals can be arranged in an order of reactivity as follows;

Mg> Zn > Fe.

2) The equation of the reaction is;

Mg(s) + 2H^+(aq) ------>Mg^2+(aq) + H2(g)

If we consider the changes in oxidation number from left to right;

The oxidation number of Mg changed from zero to +2

The oxidation number of H changed from +1 to zero

Recall that a redox reaction is a reaction in which the oxidation number of species changes from left to right in the reaction. Hence this reaction is a redox reaction.

The reducing agent experiences an increase in oxidation number. In this case, Mg is the reducing agent.

The oxidation half equation is;

Mg(s) ------> Mg^2+(aq) + 2e

The reduction half equation is;

2H^+(aq) + 2e ------> H2(g)

Answer: The molarity of final solution is 0.244 M.

Explanation:

Given: [tex]M_{1}[/tex] = 1.00 M,       [tex]V_{1}[/tex] = 0.305 L

[tex]M_{2}[/tex] = ?,                [tex]V_{2}[/tex] = 1.25 L

Formula used to calculate the molarity f resulting solution is as follows.

[tex]M_{1}V_{1} = M_{2}V_{2}[/tex]

Substitute the values into above formula as follows.

[tex]M_{1}V_{1} = M_{2}V_{2}\\1.00 M \times 0.305 L = M_{2} \times 1.25 L\\M_{2} = \frac{1.00 M \times 0.305 L}{1.25 L}\\= 0.244 M[/tex]

Thus, we can conclude that the molarity of final solution is 0.244 M.

Answer:

a.

[tex][H _{3}O {}^{ + } ] = 4.23 \times {10}^{ - 3} M[/tex]

b.

[tex][OH {}^{ - } ] = \frac{kw}{[H {}^{ + } ]} \\ [OH {}^{ - } ] = \frac{1 \times {10}^{ - 14} }{4.23 \times {10}^{ - 3} } \\ [OH {}^{ - } ] = 2.36 \times {10}^{ - 12} M[/tex]

c.

[tex]pH = - log[H {}^{ + } ] \\ pH = - log(4.23 \times {10}^{ - 3} ) \\ pH = 2.37[/tex]

d.

[tex]pOH = - log[OH {}^{ - } ] \\ = - log(2.36 \times {10}^{ - 12} ) \\ = 11.63[/tex]

Explanation:

she could waited for the saturated vapour pressure to equal the prevailing atmospheric pressure

ergo boiling to take place seeing as she had gotten the first indication that boiling had started

Answer:

sodium=atomic number 11 it electronic configuration is ,K=2, L=8,M=1 Valence is 1

oxygen= atomic number 8 it electronic configuration is K=2, L=6 Valence is 2

iron= atomic number 26 it electronic configuration is K= 2 L= 8,M=8 N=6 Valence 2

Answer: A=1

B=6

C=8

Explanation:

Answer:

The new pressure of the gas is 1080 mmHg

Explanation:

The general equation provides a way to calculate the relationship between changesnp in volume, temperature and pressure of a given mass of gas.

The general gas equation is given as P1V1/T1 = P2V2/T2

Where P1 is initial pressure of gas

V1 is initial volume of gas

T1 is initial temperature of gas

P2 is final pressure of gas

V2 is final volume of gas

T2 is final temperature of gas

From the given question, P1 = 900 mmHg, V1 = 0.8 L, T1 = 400 K, P2 = ?, V2 = 0.5 L, T2 = 300 K

Making P2 subject of the general gas equations:

P2 = P1V1T2/V2T1

P2 = (900 × 0.8 × 300) / (0.5 × 400)

P2 = 1080 mmHg

Therefore, the new pressure of the gas is 1080 mmHg.

Answer:

72.58 g/mol

Explanation:

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The relationship between the rate of diffusion and the molar mass is given by Graham's law.  A gas diffusing 1/6 times faster than hydrogen will have a molar mass of 72.58 g/mol. Thus, option d is correct.

Graham's law states the inverse relationship between the rate of diffusion and the square root of the molar mass of the gas. It is given as,

Rate = 1 ÷ √M

The molar mass of the gas that diffuses 1/6 times faster than hydrogen is calculated as,

R₁ ÷ R₂ = √ (M₂ ÷ M₁)

Here,

The molar mass of hydrogen = M₁

The molar mass of unknown gas = M₂

Rate of diffusion of hydrogen gas = R₁

Rate of diffusion of unknown gas = R₂ = 1 / 6 R₁

Substituting values:

R₁ ÷ 1/6 R₁ = √M₂ ÷ 2

6 × 1.414

= 8.485

= 84.85 g/mol ≈ 72.58 g/mol

Therefore, option d. 72.58 g/mol is the molar mass of unkown gas.

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