True or False, the central atom in a molecule is the one with the highest electron affinity.

The amount of 217 mg of an isotope is given by A(t) = 217 € -0.0171, where t is time in years since the initial amount of 217 mg

Maru [420]

The amount left after 20 years = 154.15 mg

<h3>Further explanation </h3>

The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.

Usually radioactive elements have an unstable atomic nucleus.

The main particles are emitted by radioactive elements so that they generally decay are alpha (α), beta (β) and gamma (γ) particles

The decay formula for isotope :

$\tt \large{\boxed{\bold{A(t)=217e^{-0.0171t}}}$

Then for t=20 years, the amount left :

$\tt A(t)=217e^{-0.0171\times 20}\\\\A(t)=154.15~mg$

4 0

3 years ago

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What are atoms in general

AVprozaik [17]

Atoms are the basic building blocks of ordinary matter. Atoms can join together to form molecules, which in turn form most of the objects around you.

6 0

2 years ago

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If I have 72 liters of argon gas held at a pressure of 3.4 atm and a temperature of 225k how many grams of argon do I have

andrezito [222]

Answer:

516.77 grams of Argon gas is present

Explanation:

Using the gas formula

PV = nRT

number of moles (n) = mass / molar weight or mass

P = pressure = 3.4 atm

V = volume = 72 L

R = gas constant = 0.082 L atm mol^-1 K^-1

T = temperature = 225 K

MM = molar mass of Ar = 38.984 g/mol

PV = mRT/ MM

m = PV MM / RT

m = 3.4 * 72 * 38.948 / 0.082 * 225

m = 9534.4704 / 18.45

m = 516.77 grams

the mass of Ar gas you have is 516.77 grams.

5 0

3 years ago

A thermometer having first-order dynamics with a time constant of 1 min is placed in a temperature bath at 100oF. After the ther

sveticcg [70]

Answer:

(a) See below

(b) 103.935 °F; 102.235 °F

Explanation:

The equation relating the temperature to time is

$T = T_{0} + \Delta T\left (1 - e^{-t/\tau} \right )$

1. Calculate the thermometer readings after 0.5 min and 1 min

(a) After 0.5 min

$\begin{array}{rcl}T & = & T_{0} + \Delta T\left (1 - e^{-t/\tau} \right )\\ & = & 100 + 10\left (1 - e^{-0.5/1} \right )\\ & = & 100 + 10\left (1 - e^{-0.5} \right )\\ & = & 100 + 10 (1 - 0.6065)\\ & = & 100 + 10(0.3935)\\ & = & 100 + 3.935\\ & = & 103.935\,^{\circ}F\\\end{array}$

(b) After 1 min

$\begin{array}{rcl}T & = & T_{0} + \Delta T\left (1 - e^{-t/\tau} \right )\\ & = & 100 + 10\left (1 - e^{-1/1} \right )\\ & = & 100 + 10\left (1 - e^{-1} \right )\\ & = & 100 + 10 (1 - 0.3679)\\ & = & 100 + 10(0.6321)\\ & = & 100 + 6.321\\ & = & 106.321\,^{\circ}F\\\end{array}$

2. Calculate the thermometer reading after 2.0 min

T₀ =106.321 °F

ΔT = 100 - 106.321 °F = -6.321 °F

t = t - 1, because the cooling starts 1 min late

$\begin{array}{rcl}T & = & T_{0} + \Delta T\left (1 - e^{-(t - 1)/\tau} \right )\\ & = & 106.321 - 6.321\left (1 - e^{-(2 - 1)/1} \right )\\ & = & 106.321 - 6.321\left (1 - e^{-1} \right )\\ & = & 106.321 - 6.321 (1 - 0.3679)\\ & = & 106.321 - 6.321 (0.6321)\\ & = & 106.321 - 3.996\\ & = & 102.325\,^{\circ}F\\\end{array}$

3. Plot the temperature readings as a function of time.

The graphs are shown below.

6 0

3 years ago

At 450°C, ammonia gas will decompose according to the following equation: 2 NH3 (g)  N2 (g) + 3 H2 (g) Kc = 4.50 at 475˚C An u

velikii [3]

Answer:

0.2024 M

Explanation:

For the decomposition reactio given, let's do an equilibrium chart. Let's call the initial concentration of NH₃ as C:

2NH₃(g) ⇄ N₂(g) + 3H₂(g)

C 0 0 Initial

-2x +x +3x Reacts (stoichiometry is 1:1:3)

C - 2x x 3x Equilibrium

3x = 0.252

x = 0.084 M

The equilibrium constant (Kc) is the multiplication of the concentrations of the products elevated by their coefficients, divided by the multiplication of reactants concentrations elevated by their coefficients.

Kc = ([H₂]³*[N₂])/([NH₃]²)

4.50 = [(0.252)³*(0.084)]/(C - 2*0.084)²

4.50 = 0.00533/(C - 0.168)²

4.50 = 0.00533/(C² - 0.336C + 0.028224)

4.50C² - 1.512C + 0.127008 = 0.00533

4.50C² - 1.512C + 0.121678 = 0

Solving the equation by a graphic calculator, for C > 0.168

C = 0.2024 M

4 0

3 years ago