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3 years ago

explain how fossils and other materials can tell us about the conditions of an area at the time it existed.

1 answer:

3 0

Well, if the fossil is from the sea/is an ocean animal (for example a fish) , then you can say that the land was once underwater. If the fossil is from a desert, you can say that the land was once a desert, etc.

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When 100 mL of 0.200 M NaCl(aq) and 100 mL of 0.200 M AgNO3(aq), both at 21.9 °C, are mixed in a coffee cup calorimeter, the tem

masya89 [10]

Answer:

There is 1.3 kJ heat produced(released)

Explanation:

<u>Step 1:</u> Data given

Volume of a 0.200 M Nacl solution = 100 mL = 0.1 L

Volume of a 0.200 M AgNO3 solution = 100 mL = 0.1 L

Initial temperature = 21.9 °C

Final temperature = 23.5 °C

Solid AgCl will be formed

<u>Step 2</u>: The balanced equation:

AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

AgCl(s) + NaNO3(aq) → Na+(aq) + NO3-(aq) + AgCl(s)

<u>Step 3:</u> Define the formula

Pressure is constant. → the heat evolved from the reaction is equivalent to the enthalpy of reaction.

Q=m*c*ΔT

⇒ Q = the heat transfer (in joule)

⇒ m =the mass (in grams)

⇒ c= the heat capacity (J/g°C)

⇒ ΔT = Change in temperature = T2- T1

Step 4: Calculate heat

Let's vonsider the density the same as the density of water (1g/mL)

Mass = volume * density

Mass = 200 mL * 1g/mL

Mass = 200 grams

Q= m*c*ΔT

⇒ m = 200 grams

⇒ c = the heat capacity (let's consider the heat capacity of water) = 4.184 J/g°C

⇒ ΔT = 23.5 -21.9 = 1.6°C

Q = 200 * 4.184 * 1.6 = 1338 .9 J = 1.3 kJ

There is 1.3 kJ heat produced(released)

Therefore, we assumed no heat is absorbed by the calorimeter, no heat is exchanged between the calorimeter and its surroundings, and the specific heat and mass of the solution are the same as those for water (1g/mL and 4.184 J/g°C)

7 0

3 years ago

It is desired to produce 2.25 grams of dichloromethane (CH2Cl2) by the following reaction. If the percent yield of dichlorometha

Allushta [10]

Answer:- 3.12 g carbon tetrachloride are needed.

Solution:- The balanced equation is:

$CH_4+CCl_4\rightarrow 2CH_2Cl_2$

From given actual yield and percent yield we will calculate the theoretical yield that would be further used to calculate the grams of carbon tetrachloride.

percent yield formula is:

percent yield = $(\frac{actual}{theoretical})100$

$65.5=(\frac{2.25}{theoretical})100$

$theoretical=(\frac{2.25(100)}{65.5})$

theoretical = 3.44 g

From balanced equation, there is 2:1 mol ratio between dichloethane and carbon tetrachloride.

Molar mass of dichloroethane is 84.93 gram per mol and molar mass of carbon tetrachloride is 153.82 gram per mol.

$3.44gCH_2Cl_2(\frac{1molCH_2Cl_2}{84.93gCH_2Cl_2})(\frac{1molCCl_4}{2molCH_2Cl_2})(\frac{153.82gCCl_4}{1molCCl_4})$

= $3.12gCCl_4$

So, 3.12 grams of carbon tetrachloride are needed to be reacted.

8 0

3 years ago

Concentrated HCl is 15 M (15 molar). A 500 mL quantity of this solution is diluted by adding water to give a final volume of 2.5

Murrr4er [49]

The molarity of the resulting solution obtained by diluting the stock solution is 3 M

<h3>Data obtained from the question </h3>

Molarity of stock solution (M₁) = 15 M
Volume of stock solution (V₁) = 500 mL
Volume of diluted solution (V₂) = 2.5 L = 2.5 × 1000 = 2500 mL
Molarity of diluted solution (M₂) =?

<h3>How to determine the molarity of diluted solution </h3>

M₁V₁ = M₂V₂

15 × 500 = M₂ × 2500

7500 = M₂ × 2500

Divide both side by 2500

M₂ = 7500 / 2500

M₂ = 3 M

Thus, the volume of the resulting solution is 3 M

Learn more about dilution:

brainly.com/question/15022582

#SPJ1

7 0

2 years ago

1. What is the first element on the periodic table?

Elena L [17]

Hydrogen as it has only 1 proton and therefore only an atomic mass of 1...

7 0

3 years ago

Read 2 more answers

Write a word equation for 2ZnS(s)+3O2(g) -> 2ZnS(s) + 2SO3(g)

hjlf

2ZnS(s)+3O2(g) -> 2Zns(s) + 2SO3(g)

the above given equation is unbalanced as it contains 4 moles of sulphur in the output but in the input there are only two aoms of sulphur so to balance the equation we will write the equation as given under

balanced equation is

2ZnS(s)+3O2(g) -> 2Zn(s) + 2SO3(g)

In words:

When 2 moles of solid zinc sulfide reacts with 3 moles of oxygen gas gives 2 moles of solid zinc and 2 moles of sulphur trioxide gas.

3 0

3 years ago