QUESTION 33 Which of the following correctly expresses 7,000,000,000 in scientific notation? 70 x 106 7 x 109 .7 x 10-7

EastWind [94]

Optimization helps you make better choices when you have all the data, and simulation helps you understand the possible outcomes when you don’t. Frontline Solvers enable you to combine these analytic methods, so you can make better choices for decisions you do control, taking into account the range of potential outcomes for factors you don’t control.

5 0

3 years ago

A 7.300 gram sample of aluminum was quantitatively combined with a sample of selenium to form a compound. The compound weighed 3

adelina 88 [10]

Answer:

The empirical formula is Al2Se3

Explanation:

Step 1: Data given

Mass of the sample of aluminium = 7.300 grams

Mass of the compound = 39.35 grams

Molar mass of aluminium = 26.98 g/mol

Molar mass of selenium = 78.96 g/mol

Step 2: Calculate mass of selenium

Mass of selenium = mass of compound - mass of aluminium

Mass of selenium = 39.35 - 7.3 = 32.05 grams

Step 3: Calculate moles of Al

Moles Al = Mass Al/ Molar mass Al

Moles Al = 7.300 grams / 26.98 g/mol

Moles Al = 0.2706 moles

Step 4: Calculate moles of Se

Moles Se = Mass Se / Molar mass Se

Moles Se =32.05 g / 78.96 g/mol

Moles Se = 0.4059 moles

Step 5: Divide through the smallest amount of mol

Aluminium: 0.2706 / 0.2706 = 1

Selenium: 0.4059/0.2706 = 1.5

This means for each mol aluminium, we have 1.5 moles of selenium

For each 2 moles of aluminium, we have 3 moles of selenium

The empirical formula is Al2Se3

This is aluminium(III) selenide.

8 0

3 years ago

Where would I find the elements with 8 valence electrons which have no charge?

Ierofanga [76]

Answer:

No charge, meaning that they have a stable electronic configuration.

It is mostly found in group 0, also known as noble gases.

4 0

4 years ago

Calculate the molecular mass of the element

marta [7]

Answer:

Na2SO4

2×23 + 32 + 4×16

46 + 32 +64

=142g

4 0

3 years ago

Balance the equations by inserting coefficients as needed. CaH₂ + H₂O Ca(OH)₂ + H₂

dmitriy555 [2]

The balanced equation is $CaH_{2} + 2 H_{2} O = Ca(OH)_{2} + 2 H_{2}$ .

The above equation is a redox reaction. A chemical equation is said to be balanced when the total mass of atoms on the reactant and product side are equal. This means that the number of atoms on both side must also be equal.

We have, $CaH_{2} + H_{2} O = Ca(OH)_{2} + H_{2}$ .

The number of atoms of Calcium (one on both sides) and Hydrogen(four on both sides) are equal. Whereas, there are 2 atoms of Oxygen on the right-hand side and only 1 atom of Oxygen on the left-hand side. So, we can put the coefficient of 2 on the molecule that has Oxygen on the left-hand side to balance them out. i.e.,

$CaH_{2} + 2H_{2} O = Ca(OH)_{2} + H_{2}$

Now, there are 6 atoms of Hydrogen on the left-hand side but only 4 on the right-hand side. To balance this, we can put the coefficient of 2 on the Hydrogen molecule on the right-hand side.

Thus, we get the final balanced equation as : $CaH_{2} + 2 H_{2} O = Ca(OH)_{2} + 2 H_{2}$

To read about balancing chemical equations visit brainly.com/question/11904811

4 0

2 years ago