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2 years ago

A meniscus must be considered when making which of the following measurements?

Chemistry

1 answer:

Snezhnost [94]2 years ago

5 0

Answer:

When you read a scale on the side of a container with a meniscus, such as a graduated cylinder or volumetric flask, it's important that the measurement accounts for the meniscus. Measure so that the line you are reading is even with the center of the meniscus. For water and most liquids, this is the bottom of the meniscus. For mercury, take the measurement from the top of the meniscus. In either case, you are measuring based on the center of the meniscus. For a flat meniscus, make sure the liquid is level. Usually placing the container on a lab bench does the trick.

You won't be able to take an accurate reading looking up at the liquid level or down into it. Get eye level with the meniscus. You can either pick up the glassware to bring it to your level or else bend down to take measurements in situations where you're concerned with dropping the container or spilling its contents.

Use the same method to take measurements each time so that any errors you make will be consistent.

Explanation:

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The compound AX2 decomposes according to the equation, 2 AX2(g) => 2 AX(g) + X2(g). In one experiment, AX2 was measured at va

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Answer:

0.0011 mol/L.s

Explanation:

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2 years ago

1.000 mile is equal to 1609 meters. A truck is traveling at 42.00 km/h. What is the speed of the truck in miles per hour?

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How many inner, outer, and valence electrons are present in an atom of each of the following elements?

Aneli [31]

Answer:

For a: The number of inner electrons, outer electrons and valence electrons are 28, 7 and 7 respectively.

For b: The number of inner electrons, outer electrons and valence electrons are 54, 1 and 1 respectively.

For c: The number of inner electrons, outer electrons and valence electrons are 23, 1 and 1 respectively.

For d: The number of inner electrons, outer electrons and valence electrons are 36, 2 and 2 respectively.

For e: The number of inner electrons, outer electrons and valence electrons are 2, 7 and 7 respectively.

Explanation:

Outer shell electrons are the electrons which are not tightly held by the electrons. They are called as valence electrons. The electrons present in the highest principle quantum number are known as valence electrons.

Inner shell electrons are the electrons which are tightly held by the electrons. They are called as core electrons.

Inner electrons = Total number of electrons - Valence electrons

Total number of electrons in an atom is equal to the atomic number of the element.

For the given options:

Option a: Bromine (Br)

Bromine is the 35th element of the periodic table having electronic configuration of $1s^22s^22p^63s^23p^64s^23d^{10}4p^5$

Highest principle quantum number is 4

Number of valence electrons = 7

Number of outer electrons = 7

Number of inner electrons = 35 - 7 = 28

Option b: Cesium (Cs)

Cesium is the 55th element of the periodic table having electronic configuration of $1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^66s^1$

Highest principle quantum number is 6

Number of valence electrons = 1

Number of outer electrons = 1

Number of inner electrons = 55 - 1 = 54

Option c: Chromium (Cr)

Chromium is the 24th element of the periodic table having electronic configuration of $1s^22s^22p^63s^23p^64s^13d^{5}$

Highest principle quantum number is 4

Number of valence electrons = 1

Number of outer electrons = 1

Number of inner electrons = 24 - 1 = 23

Option d: Strontium (Sr)

Strontium is the 38th element of the periodic table having electronic configuration of $1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^2$

Highest principle quantum number is 5

Number of valence electrons = 2

Number of outer electrons = 2

Number of inner electrons = 38 - 2 = 36

Option e: Fluorine (F)

Fluorine is the 9th element of the periodic table having electronic configuration of $1s^22s^22p^5$

Highest principle quantum number is 2

Number of valence electrons = 7

Number of outer electrons = 7

Number of inner electrons = 9 - 7 = 2

4 0

2 years ago

3350 J of heat is required to raise the temperature of a sample of AlF3 from 250C to 800C. What is the mass of the sample?

Aleonysh [2.5K]

Answer:

Look up the specific heat capacity of AlF₃
Calculate ΔT
Calculate the mass of AlF₃

Explanation:

The formula for for the heat (q) absorbed by an object is

q = mCΔT, where

m = the mass of the sample

C = the specific heat capacity of the sample. and

ΔT = the change in temperature

1. What you must do

Look up the specific heat capacity of AlF₃
Calculate ΔT
Calculate the mass of AlF₃

2. Sample calculation

For this example, I assume that the specific heat capacity of AlF₃ is 1.16 J·K⁻¹mol⁻¹ .

(a) Calculate ΔT

$\Delta T = T_{\text{f}} - T_{\text{i}} = 800 \, ^{\circ}\text{C} -250 \, ^{\circ}\text{C} = 550 \, ^{\circ}\text{C}$

(b) Calculate m

$\begin{array}{rcl}\text{3350 J} & = & m \times 1.16 \text{ J}\cdot\text{K}^{-1} \text{mol}^{-1}\times \text{550 K}\\3350 & = & m \times \text{638 g}^{-1}\\m & = &\dfrac{3350}{\text{638 g}^{-1}}\\\\ & = & \text{ 5.2 g}\\\end{array}\\$

6 0

2 years ago