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matrenka [14]
3 years ago
7

_____ are two or more elements that have been chemically combined. mixtures compounds atoms colloids

Chemistry
2 answers:
Anna007 [38]3 years ago
5 0

Answer: Option (b) is the correct answer.

Explanation:

When two or more atoms of different elements are chemically combined together in similar composition then the product formed is known as a compound.

For example, NaCl is an ionic compound.

Mixture is the substance in which two or more different components are mixed together in different composition. Components of a mixture never combine chemically.

For example, mud in water is a mixture.

Atom is defined as a single molecule of an element. For example, Na (sodium) atom.

A colloid is defined as a mixture in which insoluble particles are microscopically dispersed and suspended throughout another substance.

For example, milk is a colloid.

Therefore, we can conclude that compounds are two or more elements that have been chemically combined.

Ulleksa [173]3 years ago
3 0
The answer is compound. 

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A removal of the predator populations from an ecosystem would most likely result in
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2 years ago
Read 2 more answers
1. Calculate the energy change (q) of the surroundings (water) using the enthalpy equation
Rasek [7]

Answer:

Q1: 728.6 J.

Q2:

a) 668.8 J.

b) 0.3495 J/g°C.

Explanation:

<em>Q1: Calculate the energy change (q) of the surroundings (water) using the enthalpy equation:</em>

  • The amount of heat absorbed by water = Q = m.c.ΔT.

where, m is the mass of water (m = d x V = (1.0 g/mL)(24.9 mL) = 24.9 g).

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

ΔT is the temperature difference = (final T - initial T = 32.2°C - 25.2°C = 7.0°C).

<em>∴ The amount of heat absorbed by water = Q = m.c.ΔT</em> = (24.9 g)(4.18 J/g°C)(7.0°C) = 728.6 J.

<em>Q2:  Calculate the energy change (q) of the surroundings (water) using the enthalpy equation </em>

<em>qwater = m × c × ΔT.  </em>

<em>We can assume that the specific heat capacity of water is 4.18 J / (g × °C) and the density of water is 1.00 g/mL. calculate the specific heat of the metal. Use the data from your experiment for the unknown metal in your calculation.</em>

<em></em>

a) First part: the energy change (q) of the surroundings (water):

  • The amount of heat absorbed by water = Q = m.c.ΔT.

where, m is the mass of water (m = d x V = (1.0 g/mL)(25 mL) = 25 g).

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

ΔT is the temperature difference = (final T - initial T = 31.6°C - 25.2°C = 6.4°C).

<em>∴ The amount of heat absorbed by water = Q = m.c.ΔT</em> = (25 g)(4.18 J/g°C)(6.4°C) = <em>668.8 J.</em>

<em>b) second part:</em>

<em>Q water = Q unknown metal. </em>

<em>Q unknown metal =  - </em>668.8 J. (negative sign due to the heat is released from the metal to the surrounding water).

<em>Q unknown metal =  - </em>668.8 J = m.c.ΔT.

m = 27.776 g, c = ??? J/g°C, ΔT = (final T - initial T = 31.6°C - 100.5°C = - 68.9°C).

<em>- </em>668.8 J = m.c.ΔT = (27.776 g)(c)( - 68.9°C) = - 1914 c.

∴ c = (<em>- </em>668.8)/(- 1914) = 0.3495 J/g°C.

<em></em>

3 0
3 years ago
The half-life of a first-order reaction is 13 min. If the initial concentration of reactant is 0.085 M, how long would it take u
olasank [31]

Answer: It will take 8.2 minutes until the concentration decreases to 0.055 M

Explanation:

The time after which 99.9% reactions gets completed is 40 minutes

Explanation:

Expression for rate law for first order kinetics is given by:

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

where,

k = rate constant

t = age of sample

a = let initial amount of the reactant

a - x = amount left after decay process  

a) for completion of half life:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

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

k=\frac{0.693}{13min}=0.053min^{-1}

b)  Time taken for 0.085 M to decrease to 0.055 M

t=\frac{2.303}{0.053}\log\frac{0.085}{0.055}

t=8.2min

Thus it will take 8.2 minutes until the concentration decreases to 0.055 M

5 0
3 years ago
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