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3 years ago

Which step accurately describes how to measure the final burette volume?

2 answers:

4 0

To accurately measure the final volume of a solution in a burette, it is important that you read of the measurement in the lower meniscus like for water and for substances like mercury you read it on the upper meniscus. This is the standard way of reading volumes in laboratory apparatus. Also, it should be that the apparatus standing vertically in a plain surface.

LekaFEV [45]3 years ago

3 0

Answer:

The precision to measure a volume in a burette will depend on the shape of the meniscus that forms the liquid. In the case of a concave meniscus, its reading will be made at the lowest height of the liquid surface. This point should touch the upper edge in the division of the burette scale. In the case of a convex meniscus, its reading will be made at the highest height of the liquid surface. This point should touch the bottom edge in the burette scale division.

Explanation:

The accuracy when reading the correct volume in a burette depends on the type of meniscus. If the molecules of a liquid have a greater attraction to the glass wall, the meniscus will have a concave shape, for example, aqueous solutions. A requirement to measure exactly is the adjustment of the meniscus. As stated before, if the meniscus shape is concave, the volume will be read at the lowest height of the liquid surface. If the meniscus is convex, the volume will be taken at the highest height of the liquid surface. Convex menisci are formed by substances such as mercury.

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A sample of brass is put into a calorimeter (see sketch at right) that contains of water. The brass sample starts off at and the

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Complete Question

The complete question is shown on the first uploaded image

Answer:

The specific heat is $c_b = 0.402 J / g \cdot ^oC$

Explanation:

From the question we are told that

The mass of the sample is $m = 54.4 \ g$

The mass of the water is $m_w = 150.0 \ g$

The initial temperature of the sample is $T_i = 95.1 ^oC$

The initial temperature of the water is $T_{w_i} = 15^oC$

The final temperature of the water is $T = 17.6 ^oC$

Note the final temperature of water is equal to the final temperature of brass sample

The pressure is $P =1 \ atm$

Generally for according to the law of energy conservation

The heat lost by sample = The heat gain by water

The heat lost by brass sample is mathematically evaluated as

$H_L = m * c_b * [T_i - T]$

Where $c_b$ is the specific neat of the brass sample

The heat gained by water is mathematically evaluated as

$H_g = m_w *c_w * [T_w - T ]$

where $c_w$ is the specific heat of water which has a constant value of

$c_w = 4.186 joule/gram$

$H_L = H_g \ \equiv m* c_b * [T_i -T] = m_w * c_w * [T - T_w]$

substituting values

$52.4 * c_b * [95.1 - 17.6] = 150 * 4.186 * [ 17.6 - 15.0]$

$c_b = 0.402 J / g \cdot ^oC$

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3 years ago

In two or more complete sentences, compare singe displacements reactions and double displacement reactions

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Answer:

The answer is in the explanation

Explanation:

Single displacement reactions: In these reactions, a more reactive element kicks out a less reactive element from a compound.

Ex. Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)

In this example, Zn is more reactive than H, then Zn displaces H from the compound.

Double displacement reactions: In these kind of reactions 2 elements are displaced from the different compounds, these elements interchange positions.

Ex. CuCl2(aq) + 2 AgNO3(aq) → Cu(NO3)2(aq) + 2 AgCl(s)

In the example, Cu displaces Ag and Ag displaces Cu, they interchange positions.

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3 years ago

How many moles of solute are contained in 200 milliliters of a 1 m solution?

Vera_Pavlovna [14]

Answer:

0.2 moles of solute are in 200 mL

Explanation:

If we assume an aqueous solution, the solvent's density is 1g/mL

Solvent's volume = 200 mL

Solvent's density = Solvent's mass / Solvent's volume

Solvent's mass = solvent's density . solvent's volume → 200 mL . 1g/mL = 200 g

1 m means molality, we have 1 mol of solute in 1000 g of solvent, but in here the mass of solvent is 200 g. Let's make a rule of three:

1000 g of solvent have 1 mol of solute

Therefore, 200 g of solvent must have (200 .1) / 1000 = 0.2 moles

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4 years ago