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3 years ago

One way that scientists ensure that data are reliable is through

Chemistry

1 answer:

Vesna [10]3 years ago

4 0

Replicating experiments

(If u don’t mind can y mark me brainiest it would really help :) )

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True or false 12,785.000 has five significant digits.

Yuki888 [10]

Answer:

True

Explanation:

Significant digits include non-zero digits (unless the zero is between two non-zero numbers)

In 12,785.000, there are 5 non-zero digits:

1 2 7 8 5

4 0

3 years ago

Read 2 more answers

Calcium is an element. What is the smallest particle of calcium that has the same chemical properties of calcium?

Verdich [7]

Answer:

A. An Atom

Explanation:

An atom is the smallest particle of an element, having the same chemical properties as the bulk element.

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2 years ago

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The human eye is a complex sensing device. The optic nerve needs a minimum of 2.10x10^-17J of energy to trigger a series of impu

shepuryov [24]

Base on the question all about the human eye were an optic nerve of it needs an energy of 2.10x10^-17J that could trigger a series of impulses that eventually reach to the brain. So the possible photons of blue light needed for for this energy is 52 photons

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3 years ago

34. 3.15 mol of an unknown solid is placed into enough water to make 150.0 mL of solution. The solution's temperature increases

Digiron [165]

Answer:

ΔH = 2.68kJ/mol

Explanation:

The ΔH of dissolution of a reaction is defined as the heat produced per mole of reaction. We have 3.15 moles of the solid, to find the heat produced we need to use the equation:

q = m*S*ΔT

Where q is heat of reaction in J,

m is the mass of the solution in g,

S is specific heat of the solution = 4.184J/g°C

ΔT is change in temperature = 11.21°C

The mass of the solution is obtained from the volume and the density as follows:

150.0mL * (1.20g/mL) = 180.0g

Replacing:

q = 180.0g*4.184J/g°C*11.21°C

q = 8442J

q = 8.44kJ when 3.15 moles of the solid react.

The ΔH of the reaction is:

8.44kJ/3.15 mol

= 2.68kJ/mol

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3 years ago

If 42.7 of 0.208 M hydrochloric acid are needed to completely neutralize a solution of calcium hydroxide, how many grams of calc

Montano1993 [528]

Answer:

0.329 g

Explanation:

In the context of this problem, we have a chemical reaction between hydrochloric acid and calcium hydroxide. HCl is the acid here and calcium hydroxide is the base. Hence, we have an acid-base reaction, also known as neutralization reaction.

In a neutralization reaction, water is produced as a product, as well as a salt that we obtain after we exchange the cations: calcium bonds to chloride and hydrogen bonds to hydroxide (the latter is the formation of water). This means we also produce calcium chloride as a product. The overall reaction represents this as:

$Ca(OH)_2(aq)+2 HCl (aq)\rightarrow CaCl_2 (aq)+2 H_2O (l)$

Firslt of all, we wish to find the number of moles of HCl present. Having molarity and volume, this is done by applying the molarity formula. It states that molarity is equal to the rate between moles and volume:

$c_{HCl}=\frac{n_{HCl}}{V_{HCl}}$