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2 years ago

14

On a cool morning (12"C), a balloon is filled with 1.5 L of helium. By mid afternoon, the temperature has soared to 32°C. What i

s the new volume of the balloon? Selected Answer:

1 answer:

ddd [48]2 years ago

8 0

Answer:

1.6 L

Explanation:

Using Charle's law

$\frac {V_1}{T_1}=\frac {V_2}{T_2}$

Given ,

V₁ = 1.5 L

V₂ = ?

T₁ = 12 °C

T₂ = 32 °C

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15

So,

T₁ = (12 + 273.15) K = 285.15 K

T₂ = (32 + 273.15) K = 305.15 K

Using above equation as:

$\frac{1.5}{285.15}=\frac{V_2}{305.15}$

$V_2=\frac{1.5\cdot \:305.15}{285.15}$

New volume = 1.6 L

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Carbon dating of small bits of charcoal used in cave paintings has determined that some of the paintings are from 10000 to 30000

Andru [333]

The age of painting was determined from the decay kinetics of the radioactive Carbon -14 present in the painting sample.

Given that the half life of Carbon-14 is 5730 years.

Radioactive decay reactions follow first order rate kinetics.

Calculating the decay constant from half life:

λ $= \frac{0.693}{t_{1/2} }$

= $\frac{0.693}{5730 yr}$ = $1.21*10^{-4}yr^{-1}$

Setting up the radioactive rate equation:

$ln\frac{A_{t} }{A_{0} } =-kt$

Where $A_{t} = Activity after time t = 0.80microCi$

$A_{t} = initial activity = 6.4microCi$

k = decay constant = $1.21*10^{-4}yr^{-1}$

$ln\frac{0.80uCi}{6.4uCi} =-(1.21*10^{-4}yr^{-1})t$

ln 0.125 = $-(1.21*10^{-4}yr^{-1})t$

-2.079= $-(1.21*10^{-4}yr^{-1})t$

t= $\frac{2.07944}{1.21*10^{-4} } yr$

= 17185 years

t = 17185 years

Therefore age of the painting based in the radiocarbon -14 dating studies is 17185 years

6 0

2 years ago

A large cylindrical tank contains 0.750 m3 of nitrogen gas at 27°C and 7.50 * 103 Pa (absolute pressure). The tank has a tight‐f

Nuetrik [128]

Answer: The answer is 68142.4 Pa

Explanation:

Given that the initial properties of the cylindrical tank are :

Volume V1= 0.750m3

Temperature T1= 27C

Pressure P1 =7.5*10^3 Pa= 7500Pa

Final properties of the tank after decrease in volume and increase in temperature :

Volume V2 =0.480m3

Temperature T2 = 157C

Pressure P2 =?

Applying the gas law equation (Charles and Boyle's laws combined)

P1V1/T1 = P2V2/T2

(7500 * 0.750)/27 =( P2 * 0.480)/157

P2 =(7500 * 0.750* 157) / (0.480 *27)

P2 = 883125/12.96

P2 = 68142.4Pa

Therefore the pressure of the cylindrical tank after decrease in volume and increase in temperature is 68142.4Pa

8 0

2 years ago

Zinc is to be electroplated onto both sides of an iron sheet that is 20 cm2 as a galvanized sacrificial anode. It is desired to

Alexandra [31]

Answer:

The time required for the coating is 105 s

Explanation:

Zinc undergoes reduction reaction and absorbs two (2) electron ions.

The expression for the mass change at electrode $(m_{ch})$ is given as :

$\frac{m_{ch}}{M} ZF = It$

where;

M = molar mass

Z = ions charge at electrodes

F = Faraday's constant

I = current

A = area

t = time

also; $(m_{ch})$ = $(Ad) \rho$ ; replacing that into above equation; we have:

$\frac{(Ad) \rho}{M} ZF = It$ ---- equation (1)

where;

A = area

d = thickness

$\rho$ = density

From the above equation (1); The time required for coating can be calculated as;

$[ \frac{20 cm^2 *0.0025 cm*7.13g/cm^3}{65.38g/mol}*2 \frac{moles\ of \ electrons}{mole \ of \ Zn} * 9.65*10^4 \frac{C}{mole \ of \ electrons } ] = (20 A) t$

$t = \frac{2100}{20}$

= 105 s

8 0

2 years ago

A 0.0035 M aqueous solution of a particular compound has pH = 2.46. The compound is (A) a weak base (B) a weak acid (C) a strong

slava [35]

Answer:

(a) A strong acid

Explanation:

We have given the pH of the solution is 2.46

pH=2.46

So the concentration of $H^+=10^{-pH}=10^{-2.46}=0.00346$

solution having H+ concentration more than $H^+=10^{-7}$ is acidic

Since in the given solution, H+ concentration is 0.00346 M which is more than 10^{-7}[/tex] so this is an acidic solution

Note-The concentration of $H^+$ decide the behavior of the solution that is, it is acidic or basic

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2 years ago

In the formula XSO4 the symbol X could represent the element

nexus9112 [7]

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5 0

2 years ago