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3 years ago

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Chemistry

1 answer:

tatyana61 [14]3 years ago

5 0

Pure metals possess few important physical and metallic properties, such as melting point, boiling point, density, specific gravity, high malleability, ductility, and heat and electrical conductivity. These properties can be modified and enhanced by alloying it with some other metal or nonmetal, according to the need.

Alloys are made to:

Enhance the hardness of a metal: An alloy is harder than its components. Pure metals are generally soft. The hardness of a metal can be enhanced by alloying it with another metal or nonmetal.

Lower the melting point: Pure metals have a high melting point. The melting point lowers when pure metals are alloyed with other metals or nonmetals. This makes the metals easily fusible. This property is utilized to make useful alloys called solders.

Enhance tensile strength: Alloy formation increases the tensile strength of the parent metal.

Enhance corrosion resistance: Alloys are more resistant to corrosion than pure metals. Metals in pure form are chemically reactive and can be easily corroded by the surrounding atmospheric gases and moisture. Alloying a metal increases the inertness of the metal, which, in turn, increases corrosion resistance.

Modify color: The color of pure metal can be modified by alloying it with other metals or nonmetals containing suitable color pigments.

Provide better castability: One of the most essential requirements of getting good castings is the expansion of the metal on solidification. Pure molten metals undergo contraction on solidification. Metals need to be alloyed to obtain good castings because alloys

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NEED HELP ASAP ITS DUE TODAY THESE QUESTIONS

beks73 [17]

Density can be defined as the mass of the substance in unit volume.

Density = mass / volume

Hence, g/mL and kg/L can be used as the units of density.

Those units are interchangeable because when converting one unit into other one nothing will happen to the value.

That is because when converting the g into kg, you have to multiply the value by 1 x 10⁻³. When converting mL into L, you should again multiply the volume by 1 x 10⁻³. Then those 1 x 10⁻³ will cancel off and the original value will remain as same.

Answer is 2.70 g/mL.

<em>Explanation;</em>

Mass of the block = 146 g

Volume of the block = length x width x height

= 6.0 cm x 3.0 cm x 3.0 cm

= 54 cm³ = 54 mL

Density = mass / volume

= 146 g / 54 mL

= 2.70 g/mL

Answer is 3.39 g/mL.

<em>Explanation;</em>

When immersing an object in a solution, the increased volume indicates the volume of that object.

Hence,

Volume of the object = increased volume of water level

= final volume - initial volume

= 27.8 mL - 21.2 mL

= 6.6 mL

Mass of the object = 22.4 g

Density = Mass / Volume

= 22.4 g / 6.6 mL

= 3.39 g/mL

Accepted value is the value that scientists and community accept as true. This is a theoretical value.

But the measured value is the value that you obtain from doing experiments. This is the actual value.

If your measured value is more close to the accepted value, then your measured value is more precise. But, if your measured value is far away from accepted value means that your value is not precise and there may have some errors.

Answers : Percent error is 9.11 %

The element which has 7.13 g/cm³ as density is Zinc (Zn).

<em>Explanation;</em>

Percent error can be calculated by using following formula.

% error = ( (measured value - accepted value) / accepted value ) x 100%

= ( (7.78 g/cm³ - 7.13 g/cm³) / 7.13 g/cm³ ) x 100%

= 9.11 %

6 0

3 years ago

______ have no definite shape, but definite volume

NemiM [27]

Answer:

liquids

Explaination:

3 0

3 years ago

How many moles of chromium III nitrate are produced When chromium reacts with 0.85 moles of lead for nitrate to produce chromium

Pepsi [2]

0.85 moles formula units of lead nitrate will produce 0.57 moles formula units of chromium (III) nitrate.

<h3>Explanation</h3>

Typically, the oxidation state of Pb in lead nitrate tend to be +2. In other words, Pb in lead nitrate tends to exist as $\text{Pb}^{2+}$ ions. The formula for a nitrate ion is ${\text{NO}_3}^{-}$ . The charge on each of the nitrate ion is -1. The charge on the two ions should balance. As a result, each $\text{Pb}^{2+}$ ion in lead nitrate would pair up with two ${\text{NO}_3}^{-}$ ions. The formula for lead nitrate will be $\text{Pb}({\text{NO}_3})_2$ . Each formula unit of lead nitrate will contain one $\text{Pb}^{2+}$ ion and two ${\text{NO}_3}^{-}$ ions.

The "III" in the name "chromium (III) nitrate" is a Roman Numeral. It indicates that the oxidation state of Cr in chromium (III) nitrate is +3. The Cr in that compound will exist as $\text{Cr}^{3+}$ . Similarly, each $\text{Cr}^{3+}$ will pair up with three ${\text{NO}_3}^{-}$ ions. The formula for chromium (III) nitrate will be $\text{Cr}(\text{NO}_3})_3$ . Each formula unit of chromium (III) nitrate will contain one ${\text{NO}_3}^{-}$ ion and three ${\text{NO}_3}^{-}$ ions.

0.85 moles formula units of lead nitrate will contain 0.85 × 2 = 1.7 moles of ${\text{NO}_3}^{-}$ ions. Those nitrate ions will end up in 1.7 / 3 = 0.57 moles formula units of chromium (III) nitrate. As a result, the reaction will produce 0.57 moles formula units of chromium (III) nitrate.

7 0

3 years ago

Decide which element probably has a boiling point most and least similar to the boiling point of cesium.

natka813 [3]

Answer:

Take a look at the attachment below

Explanation:

Take a look at the periodic table. As you can see, Rubidium is the closest element to Cesium, and happens to have the closest boiling point to Cesium, with only a difference of about 30 degrees.

Respectively, you would think that fluorine should have the least similarity to Cesium with respect to it's boiling point, considering it is the farthest away from the element out of the 4 given. This is not an actual rule, there are no fixed trends of boiling points in the periodic table, there are some but overall the trends vary. However in this case fluorine does have the least similarity to Cesium with respect to it's boiling point, a difference of about 1,546.6 degrees.

<em>Hope that helps!</em>

5 0

3 years ago

Write one paragraph to explain what circuler motion is?

ZanzabumX [31]

Answer:

When a body moves in a circle with constant speed , it is said to be in uniform circular motion .

Explanation:

When an object moves in a circular path , its direction changes at each point .
This change in direction result in change of velocity (velocity is vector quantity which changes if direction of the object change) .However speed do not change (it is scalar quantity , not affected by Direction)

The Change in velocity produce acceleration ( a = v - u)

Hence The object always produce acceleration in uniform circular motion .So, Some force (centripetal force) is needed to keep the object in circular motion.

4 0

3 years ago

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