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3 years ago

Explain what happens to the energy in a wave when a sound is louder.

1 answer:

8 0

Greater amplitude waves have more energy and greater intensity, so they sound louder. ... The same amount of energy is spread over a greater area, so the intensity and loudness of the sound is less. This explains why even loud sounds fade away as you move farther from the source.

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What is the molarity of a NaCl stock used to make 750 ml of a dilute 10 mM solution if 5 ml of the concentrated solution was use

ch4aika [34]

Explanation:

The given data is as follows.

$M_{1}$ = 10 mM = $10 \times 10^{-3}$ M

$V_{1}$ = 750 ml, $V_{2}$ = 5 ml

$M_{2}$ = ?

Therefore, calculate the molarity of given NaCl stock as follows.

$M_{1} \times V_{1} = M_{2} \times V_{2}$

$10 \times 10^{-3} \times 750 ml = M_{2} \times 5 ml$

$M_{2}$ = 1.5 M

Thus, we can conclude that molarity of given NaCl stock is 1.5 M.

7 0

3 years ago

or a particular isomer of C 8 H 18 , the combustion reaction produces 5104.1 kJ of heat per mole of C 8 H 18 ( g ) consumed, und

beks73 [17]

Answer:

The standard enthalpy of formation of this isomer of $C_{8}H_{18}$ is -220.1 kJ/mol.

Explanation:

The given chemical reaction is as follows.

$C_{8}H_{18}(g)+ \frac{25}{2}O_{2}(g) \rightarrow 8CO_{2}(g)+9H_{2}O(g)$

$\Delta H^{o}_{rxn}= -5104.1kJ/mol$

The expression for the entropy change for the reaction is as follows.

$\Delta H^{o}_{rxn}=[8\Delta H^{o}_{f}(CO_{2}) +9\Delta H^{o}_{f}(H_{2}O)]-[\Delta H^{o}_{f}(C_{8}H_{18})+ \frac{25}{2}\Delta H^{o}_{f}(O_{2})]$

$\Delta H^{o}_{f}(H_{2}O)= -241.8kJ/mol$

$\Delta H^{o}_{f}(CO_{2})= -393.5kJ/mol$

$\Delta H^{o}_{f}(O_{2})= 0kJ/mol$

Substitute the all values in the entropy change expression.

$-5104.1kJ/mol=[8(-393.5)+9(-241.8)kJ/mol]-[\Delta H^{o}_{f}(C_{8}H_{18})+ \frac{25}{2}(0)kJ/mol]$

$-5104.1kJ/mol=-5324.2kJ/mol -\Delta H^{o}_{f}(C_{8}H_{18})$

$\Delta H^{o}_{f}(C_{8}H_{18}) =-5324.2kJ/mol +5104.1kJ/mol$

$=-220.1kJ/mol$

Therefore, The standard enthalpy of formation of this isomer of $C_{8}H_{18}$ is -220.1 kJ/mol.

4 0

3 years ago

Fre3 points Leave a random fact

andrezito [222]

Hey there! Here are 10 fun facts to brighten your day!

1. Three presidents, all Founding Fathers—John Adams, Thomas Jefferson, and James Monroe—died on July 4. Presidents Adams and Jefferson also died the same year, 1826; President Monroe died in 1831. Coincidence? You decide.

2. The Barbie doll’s full name is Barbara Millicent Roberts, from Willows, Wisconsin. Her birthday is March 9, 1959, when she was first displayed at the New York Toy Fair.

3. There actually aren’t “57 varieties” of Heinz ketchup, and never were. Company founder H.J. Heinz thought his product should have a number, and he liked 57. Hint: Hit the glass bottle on the “57,” not the bottom, to get the ketchup to flow.

4. One of President John Tyler’s grandsons is still alive today—and he was born in 1790. How is this possible? President Tyler, the 10th US president, was 63 when his son Lyon Tyler was born in 1853; Lyon’s son was born when he was 75. President Tyler’s living grandson, Harrison Tyler is 92. Lyon’s other son Lyon Jr. passed away in 2020 at the age of 95. The Tyler family still maintains the President’s home, Sherwood Forest Plantation in Virginia.

5. The tallest man ever recorded was American giant Robert Wadlow (1918–1940), who stood 8 feet 11 inches. Wadlow’s size was the result of an abnormally enlarged pituitary gland.

6. The oldest person ever to have lived (whose age could be authenticated), a French woman named Jeanne Louise Calment, was 122 years old when she died in 1997.

7. Sliced bread was first manufactured by machine and sold in the 1920s by the Chillicothe Baking Company in Missouri. It was the greatest thing since…unsliced bread?

8. The Earl of Sandwich, John Montagu, who lived in the 1700s, reportedly invented the sandwich so he wouldn’t have to leave his gambling table to eat.

9. The first college football game was played on November 6, 1869, between Rutgers and Princeton (then known as the College of New Jersey) in New Brunswick, New Jersey. Rutgers won.

10. Experiments in universities have actually been carried out to figure out how many licks it takes to get to the center of a Tootsie Pop, both with the machine and human lickers (because this is important scientific knowledge!). The results ranged from 252 to 411.

I know this was a bit extreme but I felt like I had to somewhat earn the points, I hope this has entertained you and have an extremely wonderful life!

7 0

3 years ago

2 NO + O22 NO2 is second order in NO and first order in O2. Complete the rate law for this reaction in the box below. Use the fo

riadik2000 [5.3K]

Answer : The value of rate of reaction is $1.35\times 10^{-8}Ms^{-1}$

Explanation :

Rate law : It is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

The given chemical equation is:

$2NO+O_2\rightarrow 2NO_2$