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Oksi-84 [34.3K]
3 years ago
9

Define prediction and explain how it is used to formulate a hypothesis.

Chemistry
1 answer:
melisa1 [442]3 years ago
7 0

Answer:a prediction is a scientific guess that’s solely based on known knowledge

Explanation:

A prediction is used to make a hypothesis because it goes in hand of guessing an outcome that can be tested

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onsider the following cyclic process carried out in two steps on a gas: Step 1: 42 J of heat is added to the gas, and 14 J of ex
Tema [17]

Answer:

W = -25 J

Explanation:

For a cyclic process, the variation of internal energy (ΔU) must be 0. It means that ΔU from step 1 must be equal to ΔU from step 2. For the first law of the thermodynamics, the energy must be conserved, so:

ΔU = Q - W, from each step. Q is the heat and W the work

When the heat is gained by the system, the process is endothermic, so Q >0, when the system loses heat, the process is exothermic, and Q<0. When the system is expanding W>0, and when it is compressing, W<0.

From step 1:

ΔU = 42 - 14

ΔU = 28 J

From step 2:

28 = -53 - W

W = -53 + 28

W = -25 J

7 0
3 years ago
What is the hybridization of the central atom in CO2? Hybridization = What are the approximate bond angles in this substance? Bo
const2013 [10]

Answer:

sp

Explanation:

Hybridization is the combination of atomic orbitals to yield equivalent hybrid orbitals of appropriate energy which can participate in bonding.

In every compound there is a central atom. The central atom is usually the least electronegative atom in the molecule. In this case the least electronegative atom in the molecule is carbon.

The bond between carbon and oxygen in CO2 is intermittent between a pure double and a pure triple bond. Hence, carbon is sp hybridized.

7 0
3 years ago
When potassium reacts with arsenic to form an ionic compound, each metal atom loses ____ electron(s) and each nonmetal atom gain
klasskru [66]

Answer:

When potassium reacts with arsenic to form an ionic compound, each metal atom loses 1 electron(s) and each nonmetal atom gains 3 electron(s). There must be 3 potassium atom(s) for every 1 arsenic atom(s) in the reaction.

Explanation:

We need to consider the octet rule: each atom will gain or lose electrons to have 8 electrons in its valence shell.

  • Potassium is in Group 1, so it has 1 valence electron, which will lose to form K⁺.
  • Arsenic is in Group 15, so it has 5 valence electrons. Then, it will gain 3 electrons to form As³⁻.

To have an electrical molecule between K⁺ and As³⁻, we require 3 K⁺ and 1 As³⁻, and the resulting formula is K₃As.

7 0
3 years ago
Cobalt (II) chloride exits in hydrated forms, the dehydrate and hexahydrate forms. A chemist grabs cobalt (II) chloride hexahydr
Veseljchak [2.6K]

2.48 grams.

<h3>Explanation</h3>

Start by finding the formula mass for cobalt (II) chloride and cobalt (II) chloride hexahydrate.

As a transition element in the middle d-block of the periodic table, cobalt can form ions with a plurality of charges. It is thus necessary to indicate its charge in systematic names of cobalt-containing formula.  

The cation "cobalt" in the systematic name of the salt has the Roman numeral "(II)" attached to it in brackets. As a metal, cobalt forms positively-charged ion. The one here thu has charge of +2.

Chloride ions have charges -1. Charges cancel out to produce neutral compounds. Each cobalt cation in this salt would thus pair with two chloride anions. Hence the empirical formula: \text{Co}\text{Cl}_2.

The prefix "<em>hexa-</em>" in the name cobalt (II) chloride <em>hexa</em>hydrate indicates that every formula unit of this salt contains six units of water. The hydrated salt thus has an empirical formula of \text{Co}\text{Cl}_2\cdot (\text{H}_2\text{O})_6.

Given the relative atomic mass for each of the elements, as seen on a modern periodic table of the elements:

  • Cobalt- 58.93 \text{g}\cdot \text{mol}^{-1}
  • Chloride- 35.45 \text{g}\cdot \text{mol}^{-1}
  • Hydrogen- 1.008 \text{g}\cdot \text{mol}^{-1}
  • Oxygen- 16.00 \text{g}\cdot \text{mol}^{-1}

Thus the formula mass of each compound

  • Cobalt (II) chloride \text{Co}\text{Cl}_2- 129.83 \text{g}\cdot \text{mol}^{-1}
  • Cobalt (II) chloride hexahydrate \text{Co}\text{Cl}_2\cdot (\text{H}_2\text{O})_6- 262.12 \text{g}\cdot \text{mol}^{-1}

Cobalt (II) chloride hexahydrate \text{Co}\text{Cl}_2\cdot (\text{H}_2\text{O})_6 decomposes under heat to produce cobalt (II) hexahydrate and water. Hence the equation:

\text{Co}\text{Cl}_2\cdot (\text{H}_2\text{O})_6 \stackrel{\Delta}{\to}\text{Co}\text{Cl}_2 +6 \; \text{H}_2\text{O}

Therefore

  • Molar ratio: n(\text{Co}\text{Cl}_2) : n(\text{Co}\text{Cl}_2 \cdot (\text{H}_2\text{O})_6 = 1 : 1
  • Mass ratio: m(\text{Co}\text{Cl}_2) : m(\text{Co}\text{Cl}_2 \cdot (\text{H}_2\text{O})_6) = 262.12 : 129.83

The mass ratio m(\text{Co}\text{Cl}_2) : m(\text{Co}\text{Cl}_2 \cdot (\text{H}_2\text{O})_6) indicates that 262.12 grams of cobalt (II) chloride hexahydrate decomposes to produce 129.83 grams of its corresponding anhydrous salt. Accordingly, heating 5.00 grams of the hexahydrate would  produce 2.48 grams of its anhydrate.

8 0
4 years ago
Please help with all 4, i don’t understand it
anyanavicka [17]

Answer:

1. the distance of the object is staying the same over time

2. the distance of the object is increasing over time

3. the distance of the object is increasing rapidly

4. the object started gaining distance slowly then began to rapidly increase in distance over time

6 0
3 years ago
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