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3 years ago

When are zeros significant in a value ?

Chemistry

2 answers:

Anika [276]3 years ago

6 0

This is a part of my homework tonight hope it helps!

ASHA 777 [7]3 years ago

5 0

Answer:

If the zero is between fwo nonzeros

Explanation:

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Help please I’ll mark as brainiliest

fredd [130]

Answer:

B B

W BW BW

Explanation:

Hope this helps

8 0

2 years ago

Give me number of significant figures in the number 40

dangina [55]

1 significant figure, because there is no decimal after the zero the zero doesn't count.

5 0

3 years ago

Suppose a system returns to its original overall, internal energy ((∆U) after the following changes. In step 1, 25 J of work is

Brums [2.3K]

Answer:

Heat transfer in step 2 = 47.75 J

Explanation:

Internal energy = heat + work done

U = Q + W

In a cyclic process the total internal energy change of the system = 0.

In the process there are two steps. The total heat exchange in the process is the sum of heat exchanges in the two processes.

We have to find the heat exchange in step 2.

In step 1,

W = 1.25 J Q = -37 J

$U_{1}$ = -37 + 1.25 = -35.75 J

In step 2, the internal energy change will be negative of that in step 1.

U = 35.75 J

W = -12 J

U = Q + W

35.75 = Q -12

Q = 47.75 J

Heat transfer in step 2 = 47.75 J

6 0

3 years ago

Melted candle wax has no fixed shape, but it does have a fixed volume. So, melted candle wax is a

dlinn [17]

It is a liquid because when you have a liquid, there is no definite shape. Therefore, this would be the answer because it takes the shape of its container.

Final answer: a. Liquid

7 0

3 years ago

Read 2 more answers

Use this equation for the following problems: 2NaN3 --> 2Na+3N2

olchik [2.2K]

Answer:

1) 65.0

2) 16.434 L = 16434 mL.

Explanation:

2NaN₃ → 2Na + 3N₂,

It is clear from the balanced equation that 2.0 moles of NaN₃ are decomposed to 2.0 moles of Na and 3.0 moles of N₂.

Q1: How many grams of NaN₃ are needed to make 23.6L of N₂?

Density of N₂ = 0.92 g/L which means that every 1.0 L of N₂ contains 0.92 g of N₂.

Now, we can get the mass of N₂ in 23.6 L N₂ using cross multiplication:

1.0 L of N₂ contains → 0.92 g of N₂.

23.6 L of N₂ contains → ??? g of N₂.

∴ The mass of N₂ in 23.6 L of N₂ = (23.6 L)(0.92 g)/(1.0 L) = 21.712 g.

We can get the no. of moles of 23.6 L of N₂ (21.712 g) using the relation:

n = mass/molar mass = (21.712 g)/(28.0 g/mol) = 0.775 mol.

We can get the no. of moles of NaN₃ needed to produce 0.775 mol of N₂:

using cross multiplication:

2.0 moles of NaN₃ produce → 3.0 moles of N₂, from the balanced equation.

??? mol of NaN₃ produce → 0.775 moles of N₂.

∴ The no. of moles of NaN₃ needed = (2.0 mol)(0.775 mol)/(3.0 mol) = 0.517 mol.

Finally, we can get the grams of NaN₃ needed:

mass = no. of moles x molar mass = (0.517 mol)(65.0 g/mol) = 33.6 g.

Q2: How many mL of N₂ result if 8.3 g Na are also produced?

We need to get the no. of moles of 8.3 g Na using the relation:

n = mass/atomic mass = (8.3 g)/(22.98 g/mol) = 0.36 mol.

We can get the no. of moles of N₂ produced with 0.36 mol of Na:

using cross multiplication:

2.0 moles of Na produced with → 3.0 moles of N₂, from the balanced equation.

0.36 moles of Na produced with → ??? moles of N₂.

∴ The no. of moles of N₂ needed = (3.0 mol)(0.36 mol)/(2.0 mol) = 0.54 mol.

We can get the mass of 0.54 mol of N₂:

mass = no. of moles x molar mass = (0.54 mol)(28.0 g/mol) = 15.12 g.

Now, we can get the mL of 15.12 g of N₂:

using cross multiplication:

1.0 L of N₂ contains → 0.92 g of N₂, from density of N₂ = 0.92 g/L.

??? L of N₂ contains → 15.12 g of N₂.

∴ The volume of N₂ result = (1.0 L)(15.12 g)/(0.92 g) = 16.434 L = 16434 mL.

4 0

3 years ago