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2 years ago

Which statements correctly describe the decay rates of radioactive isotopes?

Chemistry

2 answers:

Svetllana [295]2 years ago

6 0

Answer:

For plato, the answer is C: after each half tile, the amount of radioactive material is reduced by half

storchak [24]2 years ago

4 0

Answer: b} The exact time when an individual atom will decay can be accurately predicted.

c} After each half-life, the amount of radioactive material is reduced by half.

Explanation:

All radioactive decay follows first order kinetics.

Rate law expression for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant

t = time taken for decay process

a = initial amount of the reactant

a - x = amount left after decay process

Expression for calculating half life, which is the time taken by the half of the reactants to decompose is:

$t_{1/2}=\frac{0.693}{k}$

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A student places a beaker on a hot plate. To the beaker, he adds a clear liquid and a white powder. The mixture instantly begins

Elenna [48]

True, because if it wasn't a chemical reaction it would have proceeded to stay the same. but it begins to bubble.
sorry if this isn't the best answer I'm trying my best.

7 0

3 years ago

Read 2 more answers

A sample of pure tin metal is dissolved in nitric acid to produce 15.00 mL of solution containing Sn2+. When this tin solution i

Rudik [331]

Answer:

1.00 M

Explanation:

Sn^2+ reacts with KMNO4 as follows;

5Sn^2+(aq) + 2MnO4^-(aq) + 16H^+(aq) ----> 5Sn^4+(aq) + 2Mn^+(aq) + 8H2O(l)

The number of moles of MnO4^- reacted = 42.1/1000 L × 0.145 mol/L

= 0.0061 moles

If 5 moles of Sn^2+ reacts with 2 moles of MnO4^-

x moles of Sn^2+ reacts with 0.0061 moles of MnO4^-

x= 5 × 0.0061/2

x= 0.015 moles

Since the volume of the Sn^2+ solution is 15.00mL or 0.015 L

number of moles = concentration × volume

Concentration = number of moles/volume

Concentration= 0.015 moles/0.015 L

Concentration = 1 M

6 0

3 years ago

A student wants to make a 0.600 M aqueous solution of barium sulfate, BaSO4, and has a bottle containing 12.00 g of barium sulfa

love history [14]

<u>Answer: </u>The volume of the solution is 85.7 mL

<u>Explanation:</u>

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

$\text{Molarity of solution}=\frac{\text{Given mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (mL)}}$ .....(1)

We are given:

Molarity of solution = 0.600 M

Given mass of $BaSO_4$ = 12.00 g

We know, molar mass of $BaSO_4=[(1\times 137.33)+(1\times 32.07)+(4\times 16)]=233.4g/mol$

Putting values in equation 1, we get:

$0.600=\frac{12.00\times 1000}{233.4\times \text{Volume of solution}}\\\\\text{Volume of solution}=\frac{12.00\times 1000}{233.4\times 0.600}=85.68mL=85.7mL$

The rule of significant number that is applied for the problems having multiplication and division:

The least number of significant figures in any number of the problem determines the number of significant figures in the answer.

Here, the least number of significant figures is 3 that is determined by the number, 0.600. Thus, the answer must have these many significant figures only.

Hence, the volume of the solution is 85.7 mL

5 0

2 years ago

How many milliliters of 0. 0140 m na2s2o3 solution are needed to dissolve 0. 590 g of agbr? agbr(s) 2na2s2o3(aq)→na3ag(s2o3)2(aq

Marina86 [1]

The molarity of the solution can be used to give the moles and the volume of the solution. The 0.0140 M sodium thiosulfate needs 225 ml of volume.

<h3>What is molarity?</h3>

Molarity is the property of the solution that is given by the ratio of the moles of the solute to the volume of the solution in liters.

Given,

Molarity of Sodium thiosulfate = 0.0140 M

Mass of solute (AgBr) = 0.590 gm

Molar mass of AgBr = 187.77 g/mol

First moles from the mass can be calculated as,

Moles = mass ÷ molar mass

n = 0.590 g ÷ 187.77 g/mol

= 0.00314 moles

Now, the volume of the solution from molarity is calculated as,

Volume = moles ÷ molarity

= 0.00314 moles ÷ 0.0140

= 0.225 L

Therefore, 225 mL is the volume required.

Learn more about molarity here:

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3 0

1 year ago

Epinephrine (adrenaline) is a hormone secreted into the bloodstream in times of stress. It contains 59.0% C, 7.15% H, 26.20% O,

vichka [17]

Answer:

C9H13O3N

Explanation:

Take the atomic mass of C=12.0, H=1.0, O=16.0 and N=14.0.

We can draw a chart (please view this on desktop so to avoid spacing errors):

Let the mass of Epinephrine be 100g.

C H O N

mass(g) : 59 7.15 26.2 7.65

no. of moles : 59/12 =4.9167 7.15/1 = 7.15 26.2/16=1.6375 7.65/14=0.5464

(n.o.m. = mass/molar mass)

Ratio: 4.9167/0.5464 =9 7.15/0.5464=13 1.6375= 3 0.5464/0.5464 =1

(divide the n.o.m. by the smallest n.o.m., which is 0.5464 in this case, take the whole numbers)

So, the empirical formula will be: C9H13O3N

But this is still not yet the molecular formula. We have to ensure the molar mass is 183g/mol. Multiply the empirical formula by n.

So, let the molecular formula of Epinephrine be (C9H13O3N)n.

12x9n + 1x13n + 16x3n + 14n = 183

108n + 13n + 48n + 14n = 183

183 n = 183.

n = 1

Hence, the molecular formula is C9H13O3N.

3 0

3 years ago