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Elis [28]
2 years ago
6

Why is a control needed in a valid experiment?

Chemistry
1 answer:
aliina [53]2 years ago
5 0
You need a control so you have something to compare the experimental group on-- If you don't have a control group, how will you know what's changed?
You might be interested in
Select all that apply to physical and chemical properties ?
MaRussiya [10]

Answer:

•   Chemical properties can only be observed during a chemical reaction:

Chemical properties can only be established by changing a substance's chemical identity, and chemical properties are different from physical properties, which can be observed by viewing or touching a sample. The internal qualities of a substance must be altered to determine its chemical properties.

Examples:

Some common chemical properties are heat of combustion, enthalpy of formation, toxicity,

and flammability, each of which will be covered in this lesson.

•   Rusting of iron is the chemical reaction not physical because:

The rusting of iron is a chemical change because it is two substances reacting together to make a

new substance. When iron rusts, iron molecules react with oxygen molecules to make a compound

called iron oxide. Rusting would only be a physical change if iron molecules remained pure iron

throughout the process.

The equation for this reaction is: 4Fe+ 3O2 → 2Fe2O

•   Melting and boiling points are physical properties:

Yes melting and boiling points are the physical properties.  

Physical properties can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter.  

Physical properties include: appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, and many others.

•   Mass and volume are chemical properties:

No mass and volume are the extensive physical properties of matter

All properties of matter are either physical or chemical properties and physical properties are either intensive or extensive.

Extensive properties, such as mass and volume, depend on the amount of matter being measured.

Intensive properties, such as density and color, do not depend on the amount of the substance present.

Physical properties can be measured without changing a substance’s chemical identity.

•   Various components of a mixture do not combine chemically:

When various components of a mixture do not combine chemically it is a Combination of substances in which individual components do not combine chemically but retain their individual properties. Mixture in which one or more substances are distributed evenly in another substance.

When various components combine chemically then form chemical compounds that are often divided into two categories. Metals often react with nonmetals to form ionic compounds. These compounds are composed of positive and negative ions formed by adding or subtracting electrons from neutral atoms and molecules


7 0
3 years ago
Read 2 more answers
La columna de la izquierda corresponde a los tipos de sales y la columna derecha a los tipos de fórmula que presentan. Relaciona
Galina-37 [17]

Answer:

1. Hidracidas a. MX

2 Acidas c. MHXO

3. Oxacidas  b. MXO

4. Basicas d. M(OH)X

Explanation:

¡Hola!

En este caso, de acuerdo con el concepto de sal, la cual está generalmente dada por la presencia de al menos un metal y un no metal, es posible encontrar cuatro tipos de estas; hidrácidas, oxácidas, básicas y ácidas, en las que las primeras dos son neutras pero la segunda tiene presencia de oxígeno, la tercera tiene iones hidróxido adicionales y la cuarta iones hidrógeno de más.

Debido a la anterior, es posible relacionar cada pareja de la siguiente manera:

1. Hidracidas a. MX

2 Acidas c. MHXO

3. Oxacidas  b. MXO

4. Basicas d. M(OH)XO

En las que M se refiere a un metal, X a un no metal, H a hidrógeno y O a oxígeno.

¡Saludos!

3 0
2 years ago
What is a mixture called when it has its different components mixed evenly within the substance? Heterogeneous mixture Homogeneo
larisa86 [58]
It would be considered a Homogeneous Mixture. A mixture with two or more components mixed evenly is a Homogeneous mixture.

3 0
3 years ago
Read 2 more answers
Does anyone know how to do this???
Bond [772]
Simply look at the periodic table and fill in what you know based on the table

The number of protons = atomic number
The number of electrons, Which is the same as the atomic number for atoms.

The number of valence electrons that is given by the group that the element is in, the top number of each column in the periodic table.







8 0
3 years ago
Why does surface area of a reactant influence the rate of the reaction?
telo118 [61]

because it can influence how frequently and sufficiently the particles collide depending on the space it has to do so, for example a large surface area would be have a slower rate of reaction and a lower temperature. (the rate of reaction in terms of concentration, it is diffused from high to low) 
7 0
2 years ago
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