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Tresset [83]
3 years ago
12

The half-life of sodium-24 is 15 days. A laboratory technician measures out a 72 g sample. Approximately how many grams of sodiu

m-24 would remain after 45 days?
Chemistry
1 answer:
Vanyuwa [196]3 years ago
6 0

Answer:

after 45 days 9 g left

Explanation:

Given data:

Half life Na-24 = 15 days

Mass of sample = 72 g

Mass remain after 45 days = ?

Solution:

Number of half lives passed:

Number of half lives = time elapsed / half life

Number of half lives = 45 days / 15 days

Number of half lives = 3

At time zero total amount = 72 g

After first half life = 72 g/ 2= 36 g

At 2nd half life = 36 g/2 = 18 g

At 3rd half life = 18 g/2 = 9 g

Thus after 45 days 9 g left.

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What mass of potassium iodide is needed to prepare 5.60 L of a 1.13 M solution
MrMuchimi
Given that the question gives us concentration (M) and volume, we can use these so get moles. remember that Molarity (M)= mol/ Liters, so if we want the moles, then

moles= M x L

moles= 1.13 x 5.60= 6.33 moles KI

now to get the mass in grams, we need the molar mass of potassium iodide (KI) which can be determined using the periodic table and add the masses of each atom.

molar mass KI= 39.1 + 127= 166.1 g/mol

6.33 mol (166 g/ 1 mol)= 1050 grams KI


8 0
3 years ago
An aqueous solution is prepared by dissolving the salt formed by the neutralization of a weak acid by a weak base. Which stateme
Natasha_Volkova [10]

Answer: The values for Ka and Kb for the species in solution must be known before a prediction can be made

Explanation:

1. If Ka is greater than Kb, the salt solution is acidic

2. If Ka is lesser than Kb, the salt solution is basic

3. If Ka is equal to Kb, the salt solution is acidic

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What is Keg for the reaction 2502(g) + O2(g) = 2803(g)?
rewona [7]

Answer:

according to the law of circumference and the perpendicular area of a circle the answer would be c

Explanation:

4 0
2 years ago
Classify the possible combinations of signs for a reaction's ΔH and ΔS values by the resulting spontaneityA. ΔH is positive and
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Explanation:

1. Spontaneous as written at all temperatures

C. When ΔH is negative and ΔS is positive, the sign of ΔG will always be negative, and the reaction will be spontaneous at all temperatures.

2. Spontaneous in reverse at all temperatures

A. When ΔH is positive and ΔS is negative, the sign of ΔG will always be positive, and the reaction can never be spontaneous.

3. Spontaneous as written above a certain temperature

B. ΔH is positive and ΔS is positive - an endothermic reaction (positive ΔH) that also displays an increase in entropy (positive ΔS). It is the entropy term that favors the reaction. Therefore, as the temperature increases, the TΔS term in the Gibbs free energy equation will begin to predominate and ΔG will become negative.

4. Spontaneous as written below a certain temperature

D. ΔH negative and ΔS is negative -  When the reaction is exothermic (negative ΔH) but undergoes a decrease in entropy (negative ΔS), it is the enthalpy term which favors the reaction. In this case, a spontaneous reaction is dependent upon the TΔS term being small relative to the ΔH term, so that ΔG is negative. The freezing of water is an example of this type of process. It is spontaneous only at a relatively low temperature.

3 0
3 years ago
Can someone help me ;)<br> Will be marking someone brainliest !<br> Thank you...&lt;3
chubhunter [2.5K]

1. The name of this element is Carbon because there are 6 electrons in the shell.

2. Sorry I didn't learn that. And I don't know.

1. A metal is a solid substance, usually hard. On the other hand, a non-metals is a solid or gaseous material, in which the metallic properties are absent.

2. When a new substance is formed at that time we can understand that chemical reaction has taken place. It can't be reversed.

4. Neutron = no charge

Electron = negative

Proton= positive

5. Nucleus has a positive charge.

6. An atom is bigger. Because electrons are what takes up space in atoms, the result is that the size of the biggest filled orbital determines the size of the atom or ion.

6 0
3 years ago
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