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Illusion [34]
1 year ago
8

A 200. 0-ng sample of sodium-24 was stored in a lead-lined cabinet for 45 hours. The half-life of sodium-24 is 15 hours. How muc

h sodium-24 remains?
Chemistry
1 answer:
ipn [44]1 year ago
3 0

Answer:

25 gm would be left

Explanation:

45 hours is 3 half lives

200 gm  * 1/2 * 1/2 * 1/2 = 25 gm

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A 5.00-cm cube of magnesium has a mass of 217.501 g. What is the density of magnesiummetal?
Doss [256]

Answer:

d = 43.5 g/cm³

Explanation:

Given data:

Mass of magnesium cube = 217.501 g

Volume of magnesium cube = 5.00 cm³

Density of magnesium cube = ?

Solution:

Formula:

d = m/v

d = density

m = mass

v = volume

by putting values,

d = 217.501 g/ 5.00 cm³

d = 43.5 g/cm³

8 0
3 years ago
Explain how the following experimental errors affect the final calculation of the kilocalories per gram for a food item. Be spec
Ainat [17]

Answer:

a) the final kilocalories per gram for food will be less because the mass was reduced

b)the final kilocalories per gram for food will be less since

c) the final kilocalories per gram for food will be less since the reaction will eventually go to completion

d) the final kilocalories per gram for food will be more.

Explanation:

a) the final kilocalories per gram for food will be less because the mass was reduced from 110.3 to 101.3g

b)the final kilocalories per gram for food will be less since some marshmallow fell off before the reaction

c) the final kilocalories per gram for food will be less since the reaction will eventually go to completion

d) the final kilocalories per gram for food will be more since the thermometer that got stuck will add to the value of final kilocalories per gram

6 0
3 years ago
A 2.50 g sample of solid sodium hydroxide is added to 55.0 mL of 25 °C water in a foam cup (insulated from the environment) and
zlopas [31]

Answer:

37.1°C.

Explanation:

  • Firstly, we need to calculate the amount of heat (Q) released through this reaction:

<em>∵ ΔHsoln = Q/n</em>

no. of moles (n) of NaOH = mass/molar mass = (2.5 g)/(40 g/mol) = 0.0625 mol.

<em>The negative sign of ΔHsoln indicates that the reaction is exothermic.</em>

∴ Q = (n)(ΔHsoln) = (0.0625 mol)(44.51 kJ/mol) = 2.78 kJ.

  • We can use the relation:

Q = m.c.ΔT,

where, Q is the amount of heat released to water (Q = 2781.87 J).

m is the mass of water (m = 55.0 g, suppose density of water = 1.0 g/mL).

c is the specific heat capacity of water (c = 4.18 J/g.°C).

ΔT is the difference in T (ΔT = final temperature - initial temperature = final temperature - 25°C).

∴ (2781.87 J) = (55.0 g)(4.18 J/g.°C)(final temperature - 25°C)

∴ (final temperature - 25°C) = (2781.87 J)/(55.0 g)(4.18 J/g.°C) = 12.1.

<em>∴ final temperature = 25°C + 12.1 = 37.1°C.</em>

6 0
3 years ago
Atoms of metallic elements can form ionic bonds, but they aren't very good at forming covalent bonds. why?
Solnce55 [7]
<span>They have a great tendency to lose electrons</span>
7 0
3 years ago
What product of the krebs cycle is considered a waste product of the reaction?
Rufina [12.5K]
The answer is carbon dioxide 
5 0
3 years ago
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