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3 years ago

PLEASE HELP ME ANSWER THE TWO MULTIPLE CHOICE QUESTIONS!!!

Chemistry

1 answer:

Nikitich [7]3 years ago

7 0

Answer:

4.D. 2KJ

5.B. close to 0 degree celsius

Explanation:

heat absorbed= heat given out

100g * 4.2 * (x-0)= 400g * 4.2* ( 20-x) where x is the new temp reached

then x= 20

i.e. the temperature of ice increases to 5 degree celsius and the temperature of water decreases to 5 degree celsius .

hope it helps

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Give me number of significant figures in the number 40

dangina [55]

1 significant figure, because there is no decimal after the zero the zero doesn't count.

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3 years ago

Calculate the concentration of CO2 in water at 25 degrees Celsius when the pressure of CO2 over the solution is 4.5 atm. At 25 d

OLEGan [10]

Answer : The concentration of $CO_2$ is, 0.12 M

Explanation :

Using Henry's law :

$C_{CO_2}=k_H\times p_{CO_2}$

where,

$C_{CO_2}$ = concentration of $CO_2$ = ?

$p_{CO_2}$ = partial pressure of $CO_2$ = 4.5 atm

$k_H$ = Henry's law constant = $3.1\times 10^{-2}mol/L.atm$

Now put all the given values in the above formula, we get:

$C_{CO_2}=3.1\times 10^{-2}mol/L.atm\times (4.5atm)$

$C_{CO_2}=0.1395M\approx 0.12M$

Thus, the concentration of $CO_2$ is, 0.12 M

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3 years ago

If the initial velocity of the car in the previous problem (the car accelerates at 5.00 km/hr/s for 3.50 sec) is 22.6 km/hr, wha

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3 years ago

Read 2 more answers

if 5430 J of energy is used to heat 1.25 L of room temp. water (23.0 °C) whats the final temp of the water?

skelet666 [1.2K]

<span>We can use the heat equation,
Q = mcΔT </span>

<span>Where Q is the amount of energy transferred (J), m is the mass of the substance (kg), c is the specific heat (J g</span>⁻¹ °C⁻<span>¹) and ΔT is the temperature difference (°C).</span>

Density = mass / volume

The density of water = 0.997 g/mL

<span>Hence mass of 1.25 L (1250 mL) of water = 0.997 g/mL x 1250 mL</span>

Specific heat capacity of water = 4.186 J<span>/ g °C.</span>

Let's assume that there is no heat loss to the surrounding and the final temperature is T.

By applying the equation,

5430 J = 1246.25 g x 4.186 J/ g °C x (T - 23) °C
(T - 23) °C = 5430 J / 1246.25 g x 4.186 J/ g °C
(T - 23) °C = 1.04 °C
T = 1.04 °C + 23 °C
T = 24.04 °C

Hence, the final temperature of the water is 24.04 °C.

4 0

4 years ago

48g of 02 produce how many grams of Al2O3

bixtya [17]

Taking into account the reaction stoichiometry, 102 grams of Al₂O₃ are formed when 48 grams of O₂ react.

<h3>Reaction stoichiometry</h3>

In first place, the balanced reaction is:

4 Al + 3 O₂ → 2 Al₂O₃

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Al: 4 moles
O₂: 3 moles
Al₂O₃: 2 moles

The molar mass of the compounds is:

Al: 27 g/mole
O₂: 32 g/mole
Al₂O₃: 102 g/mole

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

Al: 4 moles ×27 g/mole= 108 grams
O₂: 3 moles ×32 g/mole= 96 grams
Al₂O₃: 2 moles ×102 g/mole= 204 grams

<h3>Mass of Al₂O₃ formed</h3>

The following rule of three can be applied: if by reaction stoichiometry 96 grams of O₂ form 204 grams of Al₂O₃, 48 grams of O₂ form how much mass of Al₂O₃?

$mass of Al_{2} O_{3} =\frac{48 grams of O_{2} x204 grams of Al_{2} O_{3}}{96 grams of O_{2}}$

<u><em>mass of Al₂O₃= 102 grams</em></u>

Finally, 102 grams of Al₂O₃ are formed when 48 grams of O₂ react.

Learn more about the reaction stoichiometry:

brainly.com/question/24741074

brainly.com/question/24653699

#SPJ1

3 0

2 years ago